diff --git a/js/moz-parser.js b/js/moz-parser.js
index 8d6d2a31..f7a87016 100644
--- a/js/moz-parser.js
+++ b/js/moz-parser.js
@@ -18,7 +18,7 @@ function parseMozFormat({code, styleId}) {
     'regexp':     'regexps',
   };
   const hasSingleEscapes = /([^\\]|^)\\([^\\]|$)/;
-  const parser = new parserlib.css.Parser({starHack: true});
+  const parser = new parserlib.css.Parser({starHack: true, skipValidation: true});
   const sectionStack = [{code: '', start: 0}];
   const errors = [];
   const sections = [];
diff --git a/vendor-overwrites/csslint/parserlib.js b/vendor-overwrites/csslint/parserlib.js
index 6618d4a3..11a2889c 100644
--- a/vendor-overwrites/csslint/parserlib.js
+++ b/vendor-overwrites/csslint/parserlib.js
@@ -28,85 +28,30 @@ THE SOFTWARE.
 
 self.parserlib = (() => {
 
-  //region Types
-
-  const TYPES = {
-    DEFAULT_TYPE: 0,
-    COMBINATOR_TYPE: 1,
-    MEDIA_FEATURE_TYPE: 2,
-    MEDIA_QUERY_TYPE: 3,
-    PROPERTY_NAME_TYPE: 4,
-    PROPERTY_VALUE_TYPE: 5,
-    PROPERTY_VALUE_PART_TYPE: 6,
-    SELECTOR_TYPE: 7,
-    SELECTOR_PART_TYPE: 8,
-    SELECTOR_SUB_PART_TYPE: 9,
-  };
-
-  const UNITS = {
-    em:   'length',
-    rem:  'length',
-    ex:   'length',
-    px:   'length',
-    cm:   'length',
-    mm:   'length',
-    in:   'length',
-    pt:   'length',
-    pc:   'length',
-    ch:   'length',
-    vh:   'length',
-    vw:   'length',
-    vmax: 'length',
-    vmin: 'length',
-    fr:   'length',
-    q:    'length',
-
-    deg:  'angle',
-    rad:  'angle',
-    grad: 'angle',
-    turn: 'angle',
-
-    ms:   'time',
-    s:    'time',
-
-    hz:   'frequency',
-    khz:  'frequency',
-
-    dpi:  'resolution',
-    dpcm: 'resolution',
-    dppx: 'resolution',
-    x:    'resolution',
-
-    ar:   'dimension',
-  };
-
-  //endregion
-  //region Properties
+  //#region Properties
 
   const Properties = {
-    // A
-    'align-items':               'normal | stretch | <baseline-position> | [ <overflow-position>? <self-position> ]',
-    'align-content':             '<align-content>',
-    'align-self':                '<align-self>',
-    'all':                       'initial | inherit | unset',
-    'alignment-adjust':          'auto | baseline | before-edge | text-before-edge | middle | central | ' +
-                                 'after-edge | text-after-edge | ideographic | alphabetic | hanging | ' +
-                                 'mathematical | <percentage> | <length>',
-    'alignment-baseline':        'auto | baseline | use-script | before-edge | text-before-edge | ' +
-                                 'after-edge | text-after-edge | central | middle | ideographic | alphabetic | ' +
-                                 'hanging | mathematical',
-    'animation':                 '[ <time> || <single-timing-function> || <time> || [ infinite | <number> ] || ' +
-                                 '<single-animation-direction> || <single-animation-fill-mode> || ' +
-                                 '[ running | paused ] || [ none | <ident> | <string> ] ]#',
-    'animation-delay':           '<time>#',
-    'animation-direction':       '<single-animation-direction>#',
-    'animation-duration':        '<time>#',
-    'animation-fill-mode':       '<single-animation-fill-mode>#',
+    'align-items': 'normal | stretch | <baseline-position> | [ <overflow-position>? <self-position> ]',
+    'align-content': '<align-content>',
+    'align-self': '<align-self>',
+    'all': 'initial | inherit | unset',
+    'alignment-adjust': 'auto | baseline | before-edge | text-before-edge | middle | central | ' +
+      'after-edge | text-after-edge | ideographic | alphabetic | hanging | ' +
+      'mathematical | <percentage> | <length>',
+    'alignment-baseline': 'auto | baseline | use-script | before-edge | text-before-edge | ' +
+      'after-edge | text-after-edge | central | middle | ideographic | alphabetic | ' +
+      'hanging | mathematical',
+    'animation': '[ <time> || <single-timing-function> || <time> || [ infinite | <number> ] || ' +
+      '<single-animation-direction> || <single-animation-fill-mode> || ' +
+      '[ running | paused ] || [ none | <ident> | <string> ] ]#',
+    'animation-delay': '<time>#',
+    'animation-direction': '<single-animation-direction>#',
+    'animation-duration': '<time>#',
+    'animation-fill-mode': '<single-animation-fill-mode>#',
     'animation-iteration-count': '[ <number> | infinite ]#',
-    'animation-name':            '[ none | <single-animation-name> ]#',
-    'animation-play-state':      '[ running | paused ]#',
+    'animation-name': '[ none | <single-animation-name> ]#',
+    'animation-play-state': '[ running | paused ]#',
     'animation-timing-function': '<single-timing-function>#',
-
     'appearance': 'none | auto',
     '-moz-appearance':
       'none | button | button-arrow-down | button-arrow-next | button-arrow-previous | ' +
@@ -156,535 +101,512 @@ self.parserlib = (() => {
       'push-button | hyperlink | radio | radio-button | checkbox | menu-item | tab | menu | ' +
       'menubar | pull-down-menu | pop-up-menu | list-menu | radio-group | checkbox-group | ' +
       'outline-tree | range | field | combo-box | signature | password | normal',
-
     'azimuth': '<azimuth>',
 
-    // B
-    'backdrop-filter':         '<filter-function-list> | none',
-    'backface-visibility':     'visible | hidden',
-    'background':              '[ <bg-layer> , ]* <final-bg-layer>',
-    'background-attachment':   '<attachment>#',
-    'background-blend-mode':   '<blend-mode>',
-    'background-clip':         '[ <box> | text ]#',
-    'background-color':        '<color>',
-    'background-image':        '<bg-image>#',
-    'background-origin':       '<box>#',
-    'background-position':     '<bg-position>#',
-    'background-position-x':   '[ center | [ left | right ]? <length-percentage>? ]#',
-    'background-position-y':   '[ center | [ top | bottom ]? <length-percentage>? ]#',
-    'background-repeat':       '<repeat-style>#',
-    'background-size':         '<bg-size>#',
-    'baseline-shift':          'baseline | sub | super | <percentage> | <length>',
-    'behavior':                1,
-    'binding':                 1,
-    'bleed':                   '<length>',
-    'block-size':              '<width>',
-    'bookmark-label':          '<content-list>',
-    'bookmark-level':          'none | <integer>',
-    'bookmark-state':          'open | closed',
-    'bookmark-target':         'none | <uri>',
-
-    'border-bottom-left-radius':  '<x-one-radius>',
+    'backdrop-filter': '<filter-function-list> | none',
+    'backface-visibility': 'visible | hidden',
+    'background': '[ <bg-layer> , ]* <final-bg-layer>',
+    'background-attachment': '<attachment>#',
+    'background-blend-mode': '<blend-mode>',
+    'background-clip': '[ <box> | text ]#',
+    'background-color': '<color>',
+    'background-image': '<bg-image>#',
+    'background-origin': '<box>#',
+    'background-position': '<bg-position>#',
+    'background-position-x': '[ center | [ left | right ]? <length-pct>? ]#',
+    'background-position-y': '[ center | [ top | bottom ]? <length-pct>? ]#',
+    'background-repeat': '<repeat-style>#',
+    'background-size': '<bg-size>#',
+    'baseline-shift': 'baseline | sub | super | <percentage> | <length>',
+    'behavior': 1,
+    'binding': 1,
+    'bleed': '<length>',
+    'block-size': '<width>',
+    'bookmark-label': '<content-list>',
+    'bookmark-level': 'none | <integer>',
+    'bookmark-state': 'open | closed',
+    'bookmark-target': 'none | <uri>',
+    'border-bottom-left-radius': '<x-one-radius>',
     'border-bottom-right-radius': '<x-one-radius>',
-    'border-top-left-radius':     '<x-one-radius>',
-    'border-top-right-radius':    '<x-one-radius>',
+    'border-top-left-radius': '<x-one-radius>',
+    'border-top-right-radius': '<x-one-radius>',
+    'border-boundary': 'none | parent | display',
+    'border-collapse': 'collapse | separate',
+    'border-image': '[ none | <image> ] || <border-image-slice> ' +
+      '[ / <border-image-width> | / <border-image-width>? / <border-image-outset> ]? || ' +
+      '<border-image-repeat>',
+    'border-image-outset': '<border-image-outset>',
+    'border-image-repeat': '<border-image-repeat>',
+    'border-image-slice': '<border-image-slice>',
+    'border-image-source': '<image> | none',
+    'border-image-width': '<border-image-width>',
+    'border-radius': '<border-radius>',
+    'border-spacing': '<length>{1,2}',
+    'bottom': '<width>',
+    'box-decoration-break': 'slice | clone',
+    'box-shadow': '<box-shadow>',
+    'box-sizing': 'content-box | border-box',
+    'break-after': 'auto | always | avoid | left | right | page | column | avoid-page | avoid-column',
+    'break-before': 'auto | always | avoid | left | right | page | column | avoid-page | avoid-column',
+    'break-inside': 'auto | avoid | avoid-page | avoid-column',
+    '-moz-box-align': 1,
+    '-moz-box-decoration-break': 1,
+    '-moz-box-direction': 1,
+    '-moz-box-flex': 1,
+    '-moz-box-flex-group': 1,
+    '-moz-box-lines': 1,
+    '-moz-box-ordinal-group': 1,
+    '-moz-box-orient': 1,
+    '-moz-box-pack': 1,
+    '-o-box-decoration-break': 1,
+    '-webkit-box-align': 1,
+    '-webkit-box-decoration-break': 1,
+    '-webkit-box-direction': 1,
+    '-webkit-box-flex': 1,
+    '-webkit-box-flex-group': 1,
+    '-webkit-box-lines': 1,
+    '-webkit-box-ordinal-group': 1,
+    '-webkit-box-orient': 1,
+    '-webkit-box-pack': 1,
 
-    'border-boundary':         'none | parent | display',
-    'border-collapse':         'collapse | separate',
-    'border-image':            '[ none | <image> ] || <border-image-slice> ' +
-                               '[ / <border-image-width> | / <border-image-width>? / <border-image-outset> ]? || ' +
-                               '<border-image-repeat>',
-    'border-image-outset':     '<border-image-outset>',
-    'border-image-repeat':     '<border-image-repeat>',
-    'border-image-slice':      '<border-image-slice>',
-    'border-image-source':     '<image> | none',
-    'border-image-width':      '<border-image-width>',
-    'border-radius':           '<border-radius>',
-    'border-spacing':          '<length>{1,2}',
-    'bottom':                  '<width>',
-    'box-decoration-break':    'slice | clone',
-    'box-shadow':              '<box-shadow>',
-    'box-sizing':              'content-box | border-box',
-    'break-after':             'auto | always | avoid | left | right | page | column | avoid-page | avoid-column',
-    'break-before':            'auto | always | avoid | left | right | page | column | avoid-page | avoid-column',
-    'break-inside':            'auto | avoid | avoid-page | avoid-column',
-
-    '-moz-box-align':               'start | end | center | baseline | stretch',
-    '-moz-box-decoration-break':    'slice | clone',
-    '-moz-box-direction':           'normal | reverse',
-    '-moz-box-flex':                '<number>',
-    '-moz-box-flex-group':          '<integer>',
-    '-moz-box-lines':               'single | multiple',
-    '-moz-box-ordinal-group':       '<integer>',
-    '-moz-box-orient':              'horizontal | vertical | inline-axis | block-axis',
-    '-moz-box-pack':                'start | end | center | justify',
-    '-o-box-decoration-break':      'slice | clone',
-    '-webkit-box-align':            'start | end | center | baseline | stretch',
-    '-webkit-box-decoration-break': 'slice | clone',
-    '-webkit-box-direction':        'normal | reverse',
-    '-webkit-box-flex':             '<number>',
-    '-webkit-box-flex-group':       '<integer>',
-    '-webkit-box-lines':            'single | multiple',
-    '-webkit-box-ordinal-group':    '<integer>',
-    '-webkit-box-orient':           'horizontal | vertical | inline-axis | block-axis',
-    '-webkit-box-pack':             'start | end | center | justify',
-
-    // C
-    'caret-color':       'auto | <color>',
-    'caption-side':      'top | bottom | inline-start | inline-end',
-    'clear':             'none | right | left | both | inline-start | inline-end',
-    'clip':              'rect() | inset-rect() | auto',
-    'clip-path':         '<clip-source> | <clip-path> | none',
-    'clip-rule':         'nonzero | evenodd',
-    'color':             '<color>',
-    'color-interpolation':         'auto | sRGB | linearRGB',
+    'caret-color': 'auto | <color>',
+    'caption-side': 'top | bottom | inline-start | inline-end',
+    'clear': 'none | right | left | both | inline-start | inline-end',
+    'clip': 'rect() | inset-rect() | auto',
+    'clip-path': '<clip-source> | <clip-path> | none',
+    'clip-rule': 'nonzero | evenodd',
+    'color': '<color>',
+    'color-interpolation': 'auto | sRGB | linearRGB',
     'color-interpolation-filters': 'auto | sRGB | linearRGB',
-    'color-profile':     1,
-    'color-rendering':   'auto | optimizeSpeed | optimizeQuality',
-    'column-count':      '<integer> | auto',
-    'column-fill':       'auto | balance',
-    'column-gap':        '<column-gap>',
-    'column-rule':       '<border-shorthand>',
+    'color-profile': 1,
+    'color-rendering': 'auto | optimizeSpeed | optimizeQuality',
+    'column-count': '<integer> | auto',
+    'column-fill': 'auto | balance',
+    'column-gap': '<column-gap>',
+    'column-rule': '<border-shorthand>',
     'column-rule-color': '<color>',
     'column-rule-style': '<border-style>',
     'column-rule-width': '<border-width>',
-    'column-span':       'none | all',
-    'column-width':      '<length> | auto',
-    'columns':           1,
-    'contain':           'none | strict | content | [ size || layout || style || paint ]',
+    'column-span': 'none | all',
+    'column-width': '<length> | auto',
+    'columns': 1,
+    'contain': 'none | strict | content | [ size || layout || style || paint ]',
     'contain-intrinsic-size': 'none | <length>{1,2}',
-    'content':           'normal | none | <content-list> [ / <string> ]?',
+    'content': 'normal | none | <content-list> [ / <string> ]?',
     'content-visibility': 'visible | auto | hidden',
     'counter-increment': '<counter>',
-    'counter-reset':     '<counter>',
-    'counter-set':       '<counter>',
-    'crop':              'rect() | inset-rect() | auto',
-    'cue':               'cue-after | cue-before',
-    'cue-after':         1,
-    'cue-before':        1,
-    'cursor':            '[ <uri> [ <number> <number> ]? , ]* ' +
-                         '[ auto | default | none | context-menu | help | pointer | progress | wait | ' +
-                         'cell | crosshair | text | vertical-text | alias | copy | move | no-drop | ' +
-                         'not-allowed | grab | grabbing | e-resize | n-resize | ne-resize | nw-resize | ' +
-                         's-resize | se-resize | sw-resize | w-resize | ew-resize | ns-resize | ' +
-                         'nesw-resize | nwse-resize | col-resize | row-resize | all-scroll | ' +
-                         'zoom-in | zoom-out ]',
+    'counter-reset': '<counter>',
+    'counter-set': '<counter>',
+    'crop': 'rect() | inset-rect() | auto',
+    'cue': 'cue-after | cue-before',
+    'cue-after': 1,
+    'cue-before': 1,
+    'cursor': '[ <uri> [ <number> <number> ]? , ]* ' +
+      '[ auto | default | none | context-menu | help | pointer | progress | wait | ' +
+      'cell | crosshair | text | vertical-text | alias | copy | move | no-drop | ' +
+      'not-allowed | grab | grabbing | e-resize | n-resize | ne-resize | nw-resize | ' +
+      's-resize | se-resize | sw-resize | w-resize | ew-resize | ns-resize | ' +
+      'nesw-resize | nwse-resize | col-resize | row-resize | all-scroll | ' +
+      'zoom-in | zoom-out ]',
 
-    // D
     'direction': 'ltr | rtl',
     'display': '[ <display-outside> || <display-inside> ] | ' +
-               '<display-listitem> | <display-internal> | <display-box> | <display-legacy> | ' +
-               // deprecated and nonstandard
-               '-webkit-box | -webkit-inline-box | -ms-flexbox',
+      '<display-listitem> | <display-internal> | <display-box> | <display-legacy> | ' +
+      // deprecated and nonstandard
+      '-webkit-box | -webkit-inline-box | -ms-flexbox',
+    'dominant-baseline': 'auto | use-script | no-change | reset-size | ideographic | alphabetic | ' +
+      'hanging | mathematical | central | middle | text-after-edge | text-before-edge',
+    'drop-initial-after-adjust': 'central | middle | after-edge | text-after-edge | ideographic | ' +
+      'alphabetic | mathematical | <percentage> | <length>',
+    'drop-initial-after-align': 'baseline | use-script | before-edge | text-before-edge | ' +
+      'after-edge | text-after-edge | central | middle | ideographic | alphabetic | hanging | ' +
+      'mathematical',
+    'drop-initial-before-adjust': 'before-edge | text-before-edge | central | middle | ' +
+      'hanging | mathematical | <percentage> | <length>',
+    'drop-initial-before-align': 'caps-height | baseline | use-script | before-edge | ' +
+      'text-before-edge | after-edge | text-after-edge | central | middle | ideographic | ' +
+      'alphabetic | hanging | mathematical',
+    'drop-initial-size': 'auto | line | <length-pct>',
+    'drop-initial-value': '<integer>',
 
-    'dominant-baseline':          'auto | use-script | no-change | reset-size | ideographic | alphabetic | ' +
-                                  'hanging | mathematical | central | middle | text-after-edge | text-before-edge',
-    'drop-initial-after-adjust':  'central | middle | after-edge | text-after-edge | ideographic | alphabetic | ' +
-                                  'mathematical | <percentage> | <length>',
-    'drop-initial-after-align':   'baseline | use-script | before-edge | text-before-edge | after-edge | ' +
-                                  'text-after-edge | central | middle | ideographic | alphabetic | hanging | ' +
-                                  'mathematical',
-    'drop-initial-before-adjust': 'before-edge | text-before-edge | central | middle | hanging | mathematical | ' +
-                                  '<percentage> | <length>',
-    'drop-initial-before-align':  'caps-height | baseline | use-script | before-edge | text-before-edge | ' +
-                                  'after-edge | text-after-edge | central | middle | ideographic | alphabetic | ' +
-                                  'hanging | mathematical',
-    'drop-initial-size':          'auto | line | <length-percentage>',
-    'drop-initial-value':         '<integer>',
-
-    // E
-    'elevation':         '<angle> | below | level | above | higher | lower',
-    'empty-cells':       'show | hide',
+    'elevation': '<angle> | below | level | above | higher | lower',
+    'empty-cells': 'show | hide',
     'enable-background': 1,
 
-    // F
-    'fill':           '<paint>',
-    'fill-opacity':   '<opacity-value>',
-    'fill-rule':      'nonzero | evenodd',
-    'filter':         '<filter-function-list> | none',
-    'fit':            'fill | hidden | meet | slice',
-    'fit-position':   1,
-    'flex':           '<flex-shorthand>',
-    'flex-basis':     '<width>',
+    'fill': '<paint>',
+    'fill-opacity': '<opacity-value>',
+    'fill-rule': 'nonzero | evenodd',
+    'filter': '<filter-function-list> | none',
+    'fit': 'fill | hidden | meet | slice',
+    'fit-position': 1,
+    'flex': '<flex-shorthand>',
+    'flex-basis': '<width>',
     'flex-direction': 'row | row-reverse | column | column-reverse',
-    'flex-flow':      '<flex-direction> || <flex-wrap>',
-    'flex-grow':      '<number>',
-    'flex-shrink':    '<number>',
-    'flex-wrap':      'nowrap | wrap | wrap-reverse',
-    'float':          'left | right | none | inline-start | inline-end',
-    'float-offset':   1,
-    'flood-color':    1,
-    'flood-opacity':  '<opacity-value>',
-    'font':           '<font-shorthand> | caption | icon | menu | message-box | small-caption | status-bar',
-    'font-family':    '<font-family>',
-    'font-feature-settings':   '<feature-tag-value># | normal',
-    'font-kerning':            'auto | normal | none',
-    'font-language-override':  'normal | <string>',
-    'font-optical-sizing':     'auto | none',
-    'font-palette':            'none | normal | light | dark | <ident>',
-    'font-size':               '<font-size>',
-    'font-size-adjust':        '<number> | none',
-    'font-stretch':            '<font-stretch>',
-    'font-style':              '<font-style>',
-    'font-synthesis':          'none | [ weight || style ]',
-    'font-synthesis-style':    'auto | none',
-    'font-synthesis-weight':   'auto | none',
+    'flex-flow': '<flex-direction> || <flex-wrap>',
+    'flex-grow': '<number>',
+    'flex-shrink': '<number>',
+    'flex-wrap': 'nowrap | wrap | wrap-reverse',
+    'float': 'left | right | none | inline-start | inline-end',
+    'float-offset': 1,
+    'flood-color': 1,
+    'flood-opacity': '<opacity-value>',
+    // matching no-pct first because Matcher doesn't retry for a longer match in nested definitions
+    'font': '<font-short-tweak-no-pct>? <font-short-core> | ' +
+      '[ <font-short-tweak-no-pct> || <percentage> ]? <font-short-core> | ' +
+      'caption | icon | menu | message-box | small-caption | status-bar',
+    'font-family': '<font-family>',
+    'font-feature-settings': '<feature-tag-value># | normal',
+    'font-kerning': 'auto | normal | none',
+    'font-language-override': 'normal | <string>',
+    'font-optical-sizing': 'auto | none',
+    'font-palette': 'none | normal | light | dark | <ident>',
+    'font-size': '<font-size>',
+    'font-size-adjust': '<number> | none',
+    'font-stretch': '<font-stretch>',
+    'font-style': '<font-style>',
+    'font-synthesis': 'none | [ weight || style ]',
+    'font-synthesis-style': 'auto | none',
+    'font-synthesis-weight': 'auto | none',
     'font-synthesis-small-caps': 'auto | none',
-    'font-variant':            '<font-variant> | normal | none',
+    'font-variant': '<font-variant> | normal | none',
     'font-variant-alternates': '<font-variant-alternates> | normal',
-    'font-variant-caps':       '<font-variant-caps> | normal',
+    'font-variant-caps': '<font-variant-caps> | normal',
     'font-variant-east-asian': '<font-variant-east-asian> | normal',
-    'font-variant-emoji':      'auto | text | emoji | unicode',
-    'font-variant-ligatures':  '<font-variant-ligatures> | normal | none',
-    'font-variant-numeric':    '<font-variant-numeric> | normal',
-    'font-variant-position':   'normal | sub | super',
+    'font-variant-emoji': 'auto | text | emoji | unicode',
+    'font-variant-ligatures': '<font-variant-ligatures> | normal | none',
+    'font-variant-numeric': '<font-variant-numeric> | normal',
+    'font-variant-position': 'normal | sub | super',
     'font-variation-settings': 'normal | [ <string> <number> ]#',
-    'font-weight':             '<font-weight>',
-    '-ms-flex-align': 'start | end | center | stretch | baseline',
-    '-ms-flex-order': '<number>',
-    '-ms-flex-pack':  'start | end | center | justify',
+    'font-weight': '<font-weight>',
+    '-ms-flex-align': 1,
+    '-ms-flex-order': 1,
+    '-ms-flex-pack': 1,
 
-    // G
-    'gap':                          '<row-gap> <column-gap>?',
+    'gap': '<row-gap> <column-gap>?',
     'glyph-orientation-horizontal': '<glyph-angle>',
-    'glyph-orientation-vertical':   'auto | <glyph-angle>',
+    'glyph-orientation-vertical': 'auto | <glyph-angle>',
 
     'grid': '<grid-template> | <grid-template-rows> / [ auto-flow && dense? ] <grid-auto-columns>? | ' +
-            '[ auto-flow && dense? ] <grid-auto-rows>? / <grid-template-columns>',
-    'grid-area':         '<grid-line> [ / <grid-line> ]{0,3}',
+      '[ auto-flow && dense? ] <grid-auto-rows>? / <grid-template-columns>',
+    'grid-area': '<grid-line> [ / <grid-line> ]{0,3}',
     'grid-auto-columns': '<grid-auto-columns>',
-    'grid-auto-flow':    '[ row | column ] || dense',
-    'grid-auto-rows':    '<grid-auto-rows>',
-    'grid-column':       '<grid-line> [ / <grid-line> ]?',
+    'grid-auto-flow': '[ row | column ] || dense',
+    'grid-auto-rows': '<grid-auto-rows>',
+    'grid-column': '<grid-line> [ / <grid-line> ]?',
     'grid-column-start': '<grid-line>',
-    'grid-column-end':   '<grid-line>',
-    'grid-row':          '<grid-line> [ / <grid-line> ]?',
-    'grid-row-start':    '<grid-line>',
-    'grid-row-end':      '<grid-line>',
-    'grid-template':     'none | [ <grid-template-rows> / <grid-template-columns> ] | ' +
-                         '[ <line-names>? <string> <track-size>? <line-names>? ]+ [ / <explicit-track-list> ]?',
-    'grid-template-areas':   'none | <string>+',
+    'grid-column-end': '<grid-line>',
+    'grid-row': '<grid-line> [ / <grid-line> ]?',
+    'grid-row-start': '<grid-line>',
+    'grid-row-end': '<grid-line>',
+    'grid-template': 'none | [ <grid-template-rows> / <grid-template-columns> ] | ' +
+      '[ <line-names>? <string> <track-size>? <line-names>? ]+ [ / <explicit-track-list> ]?',
+    'grid-template-areas': 'none | <string>+',
     'grid-template-columns': '<grid-template-columns>',
-    'grid-template-rows':    '<grid-template-rows>',
-    'grid-row-gap':          '<row-gap>',
-    'grid-column-gap':       '<column-gap>',
-    'grid-gap':              '<row-gap> <column-gap>?',
+    'grid-template-rows': '<grid-template-rows>',
+    'grid-row-gap': '<row-gap>',
+    'grid-column-gap': '<column-gap>',
+    'grid-gap': '<row-gap> <column-gap>?',
 
-    // H
     'hanging-punctuation': 'none | [ first || [ force-end | allow-end ] || last ]',
-    'height':              'auto | <width-height>',
-    'hyphenate-after':     '<integer> | auto',
-    'hyphenate-before':    '<integer> | auto',
+    'height': 'auto | <width-height>',
+    'hyphenate-after': '<integer> | auto',
+    'hyphenate-before': '<integer> | auto',
     'hyphenate-character': '<string> | auto',
-    'hyphenate-lines':     'no-limit | <integer>',
-    'hyphenate-resource':  1,
-    'hyphens':             'none | manual | auto',
+    'hyphenate-lines': 'no-limit | <integer>',
+    'hyphenate-resource': 1,
+    'hyphens': 'none | manual | auto',
 
-    // I
-    'icon':              1,
+    'icon': 1,
     'image-orientation': 'from-image | none | [ <angle> || flip ]',
-    'image-rendering':   'auto | smooth | high-quality | crisp-edges | pixelated | optimizeSpeed | optimizeQuality',
-    'image-resolution':  1,
-    'ime-mode':          'auto | normal | active | inactive | disabled',
-    'inline-box-align':  'last | <integer>',
-    'inline-size':       '<width>',
-    'inset':             '<width>{1,4}',
-    'inset-block':       '<width>{1,2}',
-    'inset-block-end':   '<width>',
+    'image-rendering': 'auto | smooth | high-quality | crisp-edges | pixelated | ' +
+      'optimizeSpeed | optimizeQuality',
+    'image-resolution': 1,
+    'ime-mode': 'auto | normal | active | inactive | disabled',
+    'inline-box-align': 'last | <integer>',
+    'inline-size': '<width>',
+    'inset': '<width>{1,4}',
+    'inset-block': '<width>{1,2}',
+    'inset-block-end': '<width>',
     'inset-block-start': '<width>',
-    'inset-inline':       '<width>{1,2}',
-    'inset-inline-end':   '<width>',
+    'inset-inline': '<width>{1,2}',
+    'inset-inline-end': '<width>',
     'inset-inline-start': '<width>',
-    'isolation':         'auto | isolate',
+    'isolation': 'auto | isolate',
 
-    // J
     'justify-content': '<justify-content>',
-    'justify-items':   'normal | stretch | <baseline-position> | [ <overflow-position>? <self-position> ] | ' +
-                       '[ legacy || [ left | right | center ] ]',
-    'justify-self':    '<justify-self>',
+    'justify-items': 'normal | stretch | <baseline-position> | ' +
+      '[ <overflow-position>? <self-position> ] | ' +
+      '[ legacy || [ left | right | center ] ]',
+    'justify-self': '<justify-self>',
 
-    // K
     'kerning': 'auto | <length>',
 
-    // L
-    'left':                   '<width>',
-    'letter-spacing':         '<length> | normal',
-    'line-height':            '<line-height>',
-    'line-break':             'auto | loose | normal | strict | anywhere',
-    'line-stacking':          1,
-    'line-stacking-ruby':     'exclude-ruby | include-ruby',
-    'line-stacking-shift':    'consider-shifts | disregard-shifts',
+    'left': '<width>',
+    'letter-spacing': '<length> | normal',
+    'line-height': '<line-height>',
+    'line-break': 'auto | loose | normal | strict | anywhere',
+    'line-stacking': 1,
+    'line-stacking-ruby': 'exclude-ruby | include-ruby',
+    'line-stacking-shift': 'consider-shifts | disregard-shifts',
     'line-stacking-strategy': 'inline-line-height | block-line-height | max-height | grid-height',
-    'list-style':             1,
-    'list-style-image':       '<uri> | none',
-    'list-style-position':    'inside | outside',
-    'list-style-type':
-      '<string> | disc | circle | square | decimal | decimal-leading-zero | lower-roman | ' +
-      'upper-roman | lower-greek | lower-latin | upper-latin | armenian | ' +
+    'list-style': 1,
+    'list-style-image': '<uri> | none',
+    'list-style-position': 'inside | outside',
+    'list-style-type': '<string> | disc | circle | square | decimal | decimal-leading-zero | ' +
+      'lower-roman | upper-roman | lower-greek | lower-latin | upper-latin | armenian | ' +
       'georgian | lower-alpha | upper-alpha | none',
 
-    // M
-    'margin':             '<width>{1,4}',
-    'margin-bottom':      '<width>',
-    'margin-left':        '<width>',
-    'margin-right':       '<width>',
-    'margin-top':         '<width>',
-    'margin-block':       '<width>{1,2}',
-    'margin-block-end':   '<width>',
+    'margin': '<width>{1,4}',
+    'margin-bottom': '<width>',
+    'margin-left': '<width>',
+    'margin-right': '<width>',
+    'margin-top': '<width>',
+    'margin-block': '<width>{1,2}',
+    'margin-block-end': '<width>',
     'margin-block-start': '<width>',
-    'margin-inline':       '<width>{1,2}',
-    'margin-inline-end':   '<width>',
+    'margin-inline': '<width>{1,2}',
+    'margin-inline-end': '<width>',
     'margin-inline-start': '<width>',
-    'mark':               1,
-    'mark-after':         1,
-    'mark-before':        1,
-    'marker':             1,
-    'marker-end':         1,
-    'marker-mid':         1,
-    'marker-start':       1,
-    'marks':              1,
-    'marquee-direction':  1,
+    'mark': 1,
+    'mark-after': 1,
+    'mark-before': 1,
+    'marker': 1,
+    'marker-end': 1,
+    'marker-mid': 1,
+    'marker-start': 1,
+    'marks': 1,
+    'marquee-direction': 1,
     'marquee-play-count': 1,
-    'marquee-speed':      1,
-    'marquee-style':      1,
-    'mask':               1,
-    'mask-image':         '[ none | <image> | <uri> ]#',
-    'max-height':         'none | <width-height>',
-    'max-width':          'none | <width-height>',
-    'min-height':         'auto | <width-height>',
-    'min-width':          'auto | <width-height>',
-    'max-block-size':     '<length-percentage> | none',
-    'max-inline-size':    '<length-percentage> | none',
-    'min-block-size':     '<length-percentage>',
-    'min-inline-size':    '<length-percentage>',
-    'mix-blend-mode':     '<blend-mode>',
-    'move-to':            1,
+    'marquee-speed': 1,
+    'marquee-style': 1,
+    'mask': 1,
+    'mask-image': '[ none | <image> | <uri> ]#',
+    'max-height': 'none | <width-height>',
+    'max-width': 'none | <width-height>',
+    'min-height': 'auto | <width-height>',
+    'min-width': 'auto | <width-height>',
+    'max-block-size': '<length-pct> | none',
+    'max-inline-size': '<length-pct> | none',
+    'min-block-size': '<length-pct>',
+    'min-inline-size': '<length-pct>',
+    'mix-blend-mode': '<blend-mode>',
+    'move-to': 1,
 
-    // N
-    'nav-down':  1,
+    'nav-down': 1,
     'nav-index': 1,
-    'nav-left':  1,
+    'nav-left': 1,
     'nav-right': 1,
-    'nav-up':    1,
+    'nav-up': 1,
 
-    // O
-    'object-fit':      'fill | contain | cover | none | scale-down',
+    'object-fit': 'fill | contain | cover | none | scale-down',
     'object-position': '<position>',
-    'opacity':         '<opacity-value> | <percentage>',
-    'order':           '<integer>',
-    'orphans':         '<integer>',
-    'outline':         '[ <color> | invert ] || [ auto | <border-style> ] || <border-width>',
-    'outline-color':   '<color> | invert',
-    'outline-offset':  '<length>',
-    'outline-style':   '<border-style> | auto',
-    'outline-width':   '<border-width>',
-    'overflow':        '<overflow>{1,2}',
+    'opacity': '<opacity-value> | <percentage>',
+    'order': '<integer>',
+    'orphans': '<integer>',
+    'outline': '[ <color> | invert ] || [ auto | <border-style> ] || <border-width>',
+    'outline-color': '<color> | invert',
+    'outline-offset': '<length>',
+    'outline-style': '<border-style> | auto',
+    'outline-width': '<border-width>',
+    'overflow': '<overflow>{1,2}',
     'overflow-anchor': 'auto | none',
-    'overflow-block':  '<overflow>',
+    'overflow-block': '<overflow>',
     'overflow-inline': '<overflow>',
-    'overflow-style':  1,
-    'overflow-wrap':   'normal | break-word | anywhere',
-    'overflow-x':      '<overflow>',
-    'overflow-y':      '<overflow>',
+    'overflow-style': 1,
+    'overflow-wrap': 'normal | break-word | anywhere',
+    'overflow-x': '<overflow>',
+    'overflow-y': '<overflow>',
     'overscroll-behavior': '<overscroll>{1,2}',
     'overscroll-behavior-block': '<overscroll>',
     'overscroll-behavior-inline': '<overscroll>',
     'overscroll-behavior-x': '<overscroll>',
     'overscroll-behavior-y': '<overscroll>',
 
-    // P
-    'padding':            '<padding-width>{1,4}',
-    'padding-block':       '<padding-width>{1,2}',
-    'padding-block-end':   '<padding-width>',
-    'padding-block-start': '<padding-width>',
-    'padding-bottom':     '<padding-width>',
-    'padding-inline':       '<padding-width>{1,2}',
-    'padding-inline-end':   '<padding-width>',
-    'padding-inline-start': '<padding-width>',
-    'padding-left':       '<padding-width>',
-    'padding-right':      '<padding-width>',
-    'padding-top':        '<padding-width>',
-    'page':               1,
-    'page-break-after':   'auto | always | avoid | left | right | recto | verso',
-    'page-break-before':  'auto | always | avoid | left | right | recto | verso',
-    'page-break-inside':  'auto | avoid',
-    'page-policy':        1,
-    'pause':              1,
-    'pause-after':        1,
-    'pause-before':       1,
-    'perspective':        'none | <length>',
+    'padding': '<nonnegative-len-pct>{1,4}',
+    'padding-block': '<nonnegative-len-pct>{1,2}',
+    'padding-block-end': '<nonnegative-len-pct>',
+    'padding-block-start': '<nonnegative-len-pct>',
+    'padding-bottom': '<nonnegative-len-pct>',
+    'padding-inline': '<nonnegative-len-pct>{1,2}',
+    'padding-inline-end': '<nonnegative-len-pct>',
+    'padding-inline-start': '<nonnegative-len-pct>',
+    'padding-left': '<nonnegative-len-pct>',
+    'padding-right': '<nonnegative-len-pct>',
+    'padding-top': '<nonnegative-len-pct>',
+    'page': 1,
+    'page-break-after': 'auto | always | avoid | left | right | recto | verso',
+    'page-break-before': 'auto | always | avoid | left | right | recto | verso',
+    'page-break-inside': 'auto | avoid',
+    'page-policy': 1,
+    'pause': 1,
+    'pause-after': 1,
+    'pause-before': 1,
+    'perspective': 'none | <length>',
     'perspective-origin': '<position>',
-    'phonemes':           1,
-    'pitch':              1,
-    'pitch-range':        1,
-    'place-content':      '<align-content> <justify-content>?',
-    'place-items':        '[ normal | stretch | <baseline-position> | <self-position> ] [ normal | stretch | ' +
-                          '<baseline-position> | <self-position> ]?',
-    'place-self':         '<align-self> <justify-self>?',
-    'play-during':        1,
-    'pointer-events':     'auto | none | visiblePainted | visibleFill | visibleStroke | visible | ' +
-                          'painted | fill | stroke | all',
-    'position':           'static | relative | absolute | fixed | sticky | -webkit-sticky',
+    'phonemes': 1,
+    'pitch': 1,
+    'pitch-range': 1,
+    'place-content': '<align-content> <justify-content>?',
+    'place-items': '[ normal | stretch | <baseline-position> | <self-position> ] ' +
+      '[ normal | stretch | <baseline-position> | <self-position> ]?',
+    'place-self': '<align-self> <justify-self>?',
+    'play-during': 1,
+    'pointer-events': 'auto | none | visiblePainted | visibleFill | visibleStroke | visible | ' +
+      'painted | fill | stroke | all',
+    'position': 'static | relative | absolute | fixed | sticky | -webkit-sticky',
     'presentation-level': 1,
-    'punctuation-trim':   1,
+    'punctuation-trim': 1,
 
-    // Q
     'quotes': 1,
 
-    // R
     'rendering-intent': 1,
-    'resize':           'none | both | horizontal | vertical | block | inline',
-    'rest':             1,
-    'rest-after':       1,
-    'rest-before':      1,
-    'richness':         1,
-    'right':            '<width>',
-    'rotate':           'none | [ x | y | z | <number>{3} ]? && <angle>',
-    'rotation':         1,
-    'rotation-point':   1,
-    'row-gap':          '<row-gap>',
-    'ruby-align':       1,
-    'ruby-overhang':    1,
-    'ruby-position':    1,
-    'ruby-span':        1,
+    'resize': 'none | both | horizontal | vertical | block | inline',
+    'rest': 1,
+    'rest-after': 1,
+    'rest-before': 1,
+    'richness': 1,
+    'right': '<width>',
+    'rotate': 'none | [ x | y | z | <number>{3} ]? && <angle>',
+    'rotation': 1,
+    'rotation-point': 1,
+    'row-gap': '<row-gap>',
+    'ruby-align': 1,
+    'ruby-overhang': 1,
+    'ruby-position': 1,
+    'ruby-span': 1,
 
-    // S
-    'scale':             'none | <number>{1,3}',
+    'scale': 'none | <number>{1,3}',
 
-    'scroll-behavior':             'auto | smooth',
-    'scroll-margin':               '<length>{1,4}',
-    'scroll-margin-bottom':        '<length>',
-    'scroll-margin-left':          '<length>',
-    'scroll-margin-right':         '<length>',
-    'scroll-margin-top':           '<length>',
-    'scroll-margin-block':         '<length>{1,2}',
-    'scroll-margin-block-end':     '<length>',
-    'scroll-margin-block-start':   '<length>',
-    'scroll-margin-inline':        '<length>{1,2}',
-    'scroll-margin-inline-end':    '<length>',
-    'scroll-margin-inline-start':  '<length>',
-    'scroll-padding':              '<auto-length-pct>{1,4}',
-    'scroll-padding-left':         '<auto-length-pct>',
-    'scroll-padding-right':        '<auto-length-pct>',
-    'scroll-padding-top':          '<auto-length-pct>',
-    'scroll-padding-bottom':       '<auto-length-pct>',
-    'scroll-padding-block':        '<auto-length-pct>{1,2}',
-    'scroll-padding-block-end':    '<auto-length-pct>',
-    'scroll-padding-block-start':  '<auto-length-pct>',
-    'scroll-padding-inline':       '<auto-length-pct>{1,2}',
-    'scroll-padding-inline-end':   '<auto-length-pct>',
-    'scroll-padding-inline-start': '<auto-length-pct>',
-    'scroll-snap-align':           '[ none | start | end | center ]{1,2}',
-    'scroll-snap-stop':            'normal | always',
-    'scroll-snap-type':            'none | [ x | y | block | inline | both ] [ mandatory | proximity ]?',
+    'scroll-behavior': 'auto | smooth',
+    'scroll-margin': '<length>{1,4}',
+    'scroll-margin-bottom': '<length>',
+    'scroll-margin-left': '<length>',
+    'scroll-margin-right': '<length>',
+    'scroll-margin-top': '<length>',
+    'scroll-margin-block': '<length>{1,2}',
+    'scroll-margin-block-end': '<length>',
+    'scroll-margin-block-start': '<length>',
+    'scroll-margin-inline': '<length>{1,2}',
+    'scroll-margin-inline-end': '<length>',
+    'scroll-margin-inline-start': '<length>',
+    'scroll-padding': '<width>{1,4}',
+    'scroll-padding-left': '<width>',
+    'scroll-padding-right': '<width>',
+    'scroll-padding-top': '<width>',
+    'scroll-padding-bottom': '<width>',
+    'scroll-padding-block': '<width>{1,2}',
+    'scroll-padding-block-end': '<width>',
+    'scroll-padding-block-start': '<width>',
+    'scroll-padding-inline': '<width>{1,2}',
+    'scroll-padding-inline-end': '<width>',
+    'scroll-padding-inline-start': '<width>',
+    'scroll-snap-align': '[ none | start | end | center ]{1,2}',
+    'scroll-snap-stop': 'normal | always',
+    'scroll-snap-type': 'none | [ x | y | block | inline | both ] [ mandatory | proximity ]?',
 
-    'scrollbar-color':   'auto | dark | light | <color>{2}',
-    'scrollbar-width':   'auto | thin | none',
-    'shape-inside':      'auto | outside-shape | [ <basic-shape> || shape-box ] | <image> | display',
-    'shape-rendering':   'auto | optimizeSpeed | crispEdges | geometricPrecision',
-    'size':              1,
-    'speak':             'normal | none | spell-out',
-    'speak-header':      'once | always',
-    'speak-numeral':     'digits | continuous',
+    'scrollbar-color': 'auto | dark | light | <color>{2}',
+    'scrollbar-width': 'auto | thin | none',
+    'shape-inside': 'auto | outside-shape | [ <basic-shape> || shape-box ] | <image> | display',
+    'shape-rendering': 'auto | optimizeSpeed | crispEdges | geometricPrecision',
+    'size': 1,
+    'speak': 'normal | none | spell-out',
+    'speak-header': 'once | always',
+    'speak-numeral': 'digits | continuous',
     'speak-punctuation': 'code | none',
-    'speech-rate':       1,
-    'src':               1,
-    'stop-color':        1,
-    'stop-opacity':      '<opacity-value>',
-    'stress':            1,
-    'string-set':        1,
-    'stroke':            '<paint>',
-    'stroke-dasharray':  'none | <dasharray>',
+    'speech-rate': 1,
+    'src': 1,
+    'stop-color': 1,
+    'stop-opacity': '<opacity-value>',
+    'stress': 1,
+    'string-set': 1,
+    'stroke': '<paint>',
+    'stroke-dasharray': 'none | <dasharray>',
     'stroke-dashoffset': '<percentage> | <length>',
-    'stroke-linecap':    'butt | round | square',
-    'stroke-linejoin':   'miter | round | bevel',
+    'stroke-linecap': 'butt | round | square',
+    'stroke-linejoin': 'miter | round | bevel',
     'stroke-miterlimit': '<miterlimit>',
-    'stroke-opacity':    '<opacity-value>',
-    'stroke-width':      '<percentage> | <length>',
+    'stroke-opacity': '<opacity-value>',
+    'stroke-width': '<percentage> | <length>',
 
-    // T
-    'table-layout':    'auto | fixed',
-    'tab-size':        '<number> | <length>',
-    'target':          1,
-    'target-name':     1,
-    'target-new':      1,
+    'table-layout': 'auto | fixed',
+    'tab-size': '<number> | <length>',
+    'target': 1,
+    'target-name': 1,
+    'target-new': 1,
     'target-position': 1,
-    'text-align':      '<text-align> | justify-all',
-    'text-align-all':  '<text-align>',
+    'text-align': '<text-align> | justify-all',
+    'text-align-all': '<text-align>',
     'text-align-last': '<text-align> | auto',
-    'text-anchor':     'start | middle | end',
-    'text-decoration':       '<text-decoration-line> || <text-decoration-style> || <color>',
+    'text-anchor': 'start | middle | end',
+    'text-decoration': '<text-decoration-line> || <text-decoration-style> || <color>',
     'text-decoration-color': '<color>',
-    'text-decoration-line':  '<text-decoration-line>',
-    'text-decoration-skip':  'none | [ objects || [ spaces | [ leading-spaces || trailing-spaces ] ] || ' +
-                             'edges || box-decoration ]',
+    'text-decoration-line': '<text-decoration-line>',
+    'text-decoration-skip': 'none | ' +
+      '[ objects || [ spaces | [ leading-spaces || trailing-spaces ] ] || edges || box-decoration ]',
     'text-decoration-style': '<text-decoration-style>',
-    'text-emphasis':         '<text-emphasis-style> || <color>',
-    'text-emphasis-style':   '<text-emphasis-style>',
+    'text-emphasis': '<text-emphasis-style> || <color>',
+    'text-emphasis-style': '<text-emphasis-style>',
     'text-emphasis-position': '[ over | under ] && [ right | left ]?',
-    'text-height':      1,
-    'text-indent':      '<length-percentage> && hanging? && each-line?',
-    'text-justify':     'auto | none | inter-word | inter-character',
-    'text-outline':     1,
-    'text-overflow':    'clip | ellipsis',
-    'text-rendering':   'auto | optimizeSpeed | optimizeLegibility | geometricPrecision',
-    'text-shadow':      'none | [ <color>? && <length>{2,3} ]#',
-    'text-transform':   'none | [ capitalize | uppercase | lowercase ] || full-width || full-size-kana',
+    'text-height': 1,
+    'text-indent': '<length-pct> && hanging? && each-line?',
+    'text-justify': 'auto | none | inter-word | inter-character',
+    'text-outline': 1,
+    'text-overflow': 'clip | ellipsis',
+    'text-rendering': 'auto | optimizeSpeed | optimizeLegibility | geometricPrecision',
+    'text-shadow': 'none | [ <color>? && <length>{2,3} ]#',
+    'text-transform': 'none | [ capitalize | uppercase | lowercase ] || full-width || full-size-kana',
     'text-underline-position': 'auto | [ under || [ left | right ] ]',
-    'text-wrap':        'normal | none | avoid',
-    'top':              '<width>',
-    'touch-action':     'auto | none | pan-x | pan-y | pan-left | pan-right | pan-up | pan-down | manipulation',
-    'transform':        'none | <transform-function>+',
-    'transform-box':    'border-box | fill-box | view-box',
+    'text-wrap': 'normal | none | avoid',
+    'top': '<width>',
+    'touch-action': 'auto | none | ' +
+      'pan-x | pan-y | pan-left | pan-right | pan-up | pan-down | manipulation',
+    'transform': 'none | <transform-function>+',
+    'transform-box': 'border-box | fill-box | view-box',
     'transform-origin': '<transform-origin>',
-    'transform-style':  'auto | flat | preserve-3d',
-    'transition':       '<transition>#',
+    'transform-style': 'auto | flat | preserve-3d',
+    'transition': '<transition>#',
     'transition-delay': '<time>#',
     'transition-duration': '<time>#',
     'transition-property': 'none | [ all | <ident> ]#',
     'transition-timing-function': '<single-timing-function>#',
-    'translate':        'none | <length-percentage> [ <length-percentage> <length>? ]?',
+    'translate': 'none | <length-pct> [ <length-pct> <length>? ]?',
 
-    // U
     'unicode-range': '<unicode-range>#',
-    'unicode-bidi':  'normal | embed | isolate | bidi-override | isolate-override | plaintext',
-    'user-modify':   'read-only | read-write | write-only',
-    'user-select':   'auto | text | none | contain | all',
+    'unicode-bidi': 'normal | embed | isolate | bidi-override | isolate-override | plaintext',
+    'user-modify': 'read-only | read-write | write-only',
+    'user-select': 'auto | text | none | contain | all',
 
-    // V
-    'vertical-align':    'auto | use-script | baseline | sub | super | top | text-top | central | middle | ' +
-                         'bottom | text-bottom | <percentage> | <length>',
-    'visibility':        'visible | hidden | collapse',
-    'voice-balance':     1,
-    'voice-duration':    1,
-    'voice-family':      1,
-    'voice-pitch':       1,
+    'vertical-align': 'auto | use-script | baseline | sub | super | top | text-top | ' +
+      'central | middle | bottom | text-bottom | <percentage> | <length>',
+    'visibility': 'visible | hidden | collapse',
+    'voice-balance': 1,
+    'voice-duration': 1,
+    'voice-family': 1,
+    'voice-pitch': 1,
     'voice-pitch-range': 1,
-    'voice-rate':        1,
-    'voice-stress':      1,
-    'voice-volume':      1,
-    'volume':            1,
+    'voice-rate': 1,
+    'voice-stress': 1,
+    'voice-volume': 1,
+    'volume': 1,
 
-    // W
-    'white-space':          'normal | pre | nowrap | pre-wrap | break-spaces | pre-line',
+    'white-space': 'normal | pre | nowrap | pre-wrap | break-spaces | pre-line',
     'white-space-collapse': 1,
-    'widows':               '<integer>',
-    'width':                'auto | <width-height>',
-    'will-change':          '<will-change>',
-    'word-break':           'normal | keep-all | break-all | break-word',
-    'word-spacing':         '<length> | normal',
-    'word-wrap':            'normal | break-word | anywhere',
-    'writing-mode':         'horizontal-tb | vertical-rl | vertical-lr | lr-tb | rl-tb | tb-rl | ' +
-                            'bt-rl | tb-lr | bt-lr | lr-bt | rl-bt | lr | rl | tb',
+    'widows': '<integer>',
+    'width': 'auto | <width-height>',
+    'will-change': '<will-change>',
+    'word-break': 'normal | keep-all | break-all | break-word',
+    'word-spacing': '<length> | normal',
+    'word-wrap': 'normal | break-word | anywhere',
+    'writing-mode': 'horizontal-tb | vertical-rl | vertical-lr | ' +
+      'lr-tb | rl-tb | tb-rl | bt-rl | tb-lr | bt-lr | lr-bt | rl-bt | lr | rl | tb',
 
-    // Z
     'z-index': '<integer> | auto',
-    'zoom':    '<number> | <percentage> | normal',
+    'zoom': '<number> | <percentage> | normal',
 
     // nonstandard https://compat.spec.whatwg.org/
-    '-webkit-box-reflect':       '[ above | below | right | left ]? <length>? <image>?',
-    '-webkit-text-fill-color':   '<color>',
-    '-webkit-text-stroke':       '<border-width> || <color>',
+    '-webkit-box-reflect': '[ above | below | right | left ]? <length>? <image>?',
+    '-webkit-text-fill-color': '<color>',
+    '-webkit-text-stroke': '<border-width> || <color>',
     '-webkit-text-stroke-color': '<color>',
     '-webkit-text-stroke-width': '<border-width>',
   };
@@ -708,496 +630,389 @@ self.parserlib = (() => {
     Properties[`${k}-width`] = '<border-width>' + reps;
   }
 
-  //endregion
-  //region ValidationTypes - definitions
-
-  const RX_VENDOR_PREFIX = /^-(webkit|moz|ms|o)-(.+)/i;
-  const RX_CALC = /^(-(ms|moz|o|webkit)-)?(calc|min|max|clamp)\(/i;
-
-  const ValidationTypes = {
-    simple: {
-      '<absolute-size>': 'xx-small | x-small | small | medium | large | x-large | xx-large',
-
-      '<animateable-feature>': 'scroll-position | contents | <animateable-feature-name>',
-      '<animateable-feature-name>'(part) {
-        return this['<ident>'](part) &&
-               !/^(unset|initial|inherit|will-change|auto|scroll-position|contents)$/i.test(part);
-      },
-
-      '<angle>': part => part.type === 'angle',
-      '<angle-or-0>': p => p.type === 'angle' || p.text === '0',
-
-      '<aspect-ratio>': part => part.units && lowerCmp(part.units, 'ar'),
-
-      '<attr>': p => p.type === 'function' && lowerCmp(p.name, 'attr'),
-      '<attr-fallback>': part => !/\battr\(/i.test(part.text),
-
-      '<attachment>': 'scroll | fixed | local',
-
-      '<auto-length-pct>': 'auto | <length> | <percentage>',
-
-      '<basic-shape>': 'inset() | circle() | ellipse() | polygon()',
-
-      '<bg-image>': '<image> | none',
-
-      '<blend-mode>': 'normal | multiply | screen | overlay | darken | lighten | color-dodge | ' +
-                      'color-burn | hard-light | soft-light | difference | exclusion | hue | ' +
-                      'saturation | color | luminosity',
-
-      '<border-style>': 'none | hidden | dotted | dashed | solid | double | groove | ridge | inset | outset',
-
-      '<border-width>': '<length> | thin | medium | thick',
-
-      '<box>': 'padding-box | border-box | content-box',
-
-      '<clip-source>': '<uri>',
-
-      '<column-gap>': 'normal | <length-percentage>',
-
-      '<content-distribution>': 'space-between | space-around | space-evenly | stretch',
-      '<content-position>': 'center | start | end | flex-start | flex-end',
-
-      '<width-height>': '<length-percentage> | min-content | max-content | fit-content() | ' +
-                        '-moz-available | -webkit-fill-available',
-
-      '<cubic-bezier-timing-function>': 'ease | ease-in | ease-out | ease-in-out | cubic-bezier()',
-
-      '<display-box>':      'contents | none',
-      '<display-inside>':   'flow | flow-root | table | flex | grid | ruby',
-      '<display-internal>': 'table-row-group | table-header-group | table-footer-group | table-row | ' +
-                            'table-cell | table-column-group | table-column | table-caption | ' +
-                            'ruby-base | ruby-text | ruby-base-container | ruby-text-container',
-      '<display-legacy>':   'inline-block | inline-table | inline-flex | inline-grid',
-      '<display-outside>':  'block | inline | run-in',
-
-      '<feature-tag-value>': part => part.type === 'function' && /^[A-Z0-9]{4}$/i.test(part),
-
-      // custom() isn't actually in the spec
-      '<filter-function>': 'blur() | brightness() | contrast() | custom() | drop-shadow() | grayscale() | ' +
-                           'hue-rotate() | invert() | opacity() | saturate() | sepia()',
-
-      '<fixed-breadth>': '<length-percentage>',
-
-      '<flex>': part =>
-        part.type === 'function' ||
-        part.type === 'grid' && part.value >= 0,
-
-      '<flex-basis>': '<width>',
-      '<flex-direction>': 'row | row-reverse | column | column-reverse',
-      '<flex-grow>': '<number>',
-      '<flex-shrink>': '<number>',
-      '<flex-wrap>': 'nowrap | wrap | wrap-reverse',
-
-      '<font-size>': '<absolute-size> | <relative-size> | <length-percentage>',
-      '<font-stretch>': 'normal | <percentage> | ultra-condensed | extra-condensed | condensed | semi-condensed | ' +
-                        'semi-expanded | expanded | extra-expanded | ultra-expanded',
-      '<font-style>': 'normal | italic | oblique <angle>?',
-      '<font-variant-caps>': 'small-caps | all-small-caps | petite-caps | all-petite-caps | ' +
-                             'unicase | titling-caps',
-      '<font-variant-css21>': 'normal | small-caps',
-      '<font-weight>': 'normal | bold | bolder | lighter | <number>',
-
-      '<generic-family>': 'serif | sans-serif | cursive | fantasy | monospace | system-ui | emoji | ' +
-                          'math | fangsong | ui-serif | ui-sans-serif | ui-monospace | ui-rounded',
-
-      '<geometry-box>': '<shape-box> | fill-box | stroke-box | view-box',
-
-      '<glyph-angle>': part => part.type === 'angle' && part.units === 'deg',
-
-      '<gradient>': part =>
-        part.type === 'function' &&
-        /^(?:-(?:ms|moz|o|webkit)-)?(?:repeating-)?(?:radial-|linear-|conic-)?gradient/i.test(part),
-
-      //eslint-disable-next-line no-use-before-define
-      '<hex-color>': part => part.tokenType === Tokens.HASH,
-
-      '<icccolor>': 'cielab() | cielch() | cielchab() | icc-color() | icc-named-color()',
-
-      // any identifier
-      '<ident>': part => part.type === 'identifier' || part.wasIdent,
-      '<ident-for-grid>': part =>
-        (part.type === 'identifier' || part.wasIdent) &&
-        !/^(span|auto|initial|inherit|unset|default)$/i.test(part.value),
-      '<ident-not-generic-family>'(part) {
-        return this['<ident>'](part) && !this['<generic-family>'](part);
-      },
-      '<ident-not-none>'(part) {
-        return this['<ident>'](part) && !lowerCmp(part.value, 'none');
-      },
-
-      '<image>': '<uri> | <gradient> | cross-fade()',
-
-      '<inflexible-breadth>': '<length-percentage> | min-content | max-content | auto',
-
-      '<integer>': part => part.type === 'integer',
-
-      '<length>': ({text, type}) =>
-        type === 'function' && RX_CALC.test(text) ||
-        type === 'length' ||
-        type === 'number' ||
-        type === 'integer' ||
-        text === '0',
-
-      '<length-percentage>': '<length> | <percentage>',
-
-      '<line>': part => part.type === 'integer',
-
-      '<line-height>': '<number> | <length-percentage> | normal',
-
-      '<line-names>'(part) {
-        // eslint-disable-next-line no-use-before-define
-        return part.tokenType === Tokens.LBRACKET &&
-          part.text.endsWith(']') && (
-            !part.expr ||
-            !part.expr.parts.length ||
-            part.expr.parts.every(this['<ident-for-grid>'], this)
-          );
-      },
-
-      '<miterlimit>'(part) {
-        return this['<number>'](part) && part.value >= 1;
-      },
-
-      '<nonnegative-length-or-percentage>'(part) {
-        return `${part}` === '0' ||
-               (part.type === 'function' || part.value >= 0) &&
-               (this['<length>'](part) || this['<percentage>'](part));
-      },
-      '<nonnegative-number-or-percentage>'(part) {
-        return `${part}` === '0' ||
-               (part.type === 'function' || part.value >= 0) &&
-               (this['<number>'](part) || this['<percentage>'](part));
-      },
-
-      '<number-percentage>': '<number> | <percentage>',
-
-      '<positive-integer>'(part) {
-        return this['<number>'](part) && (part.type === 'function' || part.value > 0);
-      },
-
-      //eslint-disable-next-line no-use-before-define
-      '<named-color>': part => part.text in Colors || lower(part.text) in Colors,
-
-      '<number>'(part) {
-        return part.type === 'number' || this['<integer>'](part);
-      },
-
-      '<opacity-value>'(part) {
-        return this['<number>'](part) && part.value >= 0 && part.value <= 1;
-      },
-
-      '<overflow>': 'visible | hidden | clip | scroll | auto',
-
-      '<overflow-position>': 'unsafe | safe',
-
-      '<padding-width>': '<nonnegative-length-or-percentage>',
-
-      '<percentage>': part => part.type === 'percentage' || `${part}` === '0',
-
-      '<relative-size>': 'smaller | larger',
-
-      '<row-gap>': '<column-gap>',
-
-      '<self-position>': 'center | start | end | self-start | self-end | flex-start | flex-end',
-
-      '<shape-box>': '<box> | margin-box',
-
-      '<single-animation-direction>': 'normal | reverse | alternate | alternate-reverse',
-      '<single-animation-fill-mode>': 'none | forwards | backwards | both',
-      '<single-animation-name>'(part) {
-        return this['<ident>'](part) &&
-               /^-?[a-z_][-a-z0-9_]+$/i.test(part) &&
-               !/^(none|unset|initial|inherit)$/i.test(part);
-      },
-
-      '<step-timing-function>': 'step-start | step-end | steps()',
-
-      '<string>': part => part.type === 'string',
-
-      '<text-align>': 'start | end | left | right | center | justify | match-parent',
-
-      '<text-decoration-style>': 'solid | double | dotted | dashed | wavy',
-
-      '<time>': part => part.type === 'time',
-
-      '<track-breadth>': '<length-percentage> | <flex> | min-content | max-content | auto',
-
-      '<transform-function>': 'matrix() | translate() | translateX() | translateY() | ' +
-                              'scale() | scaleX() | scaleY() | ' +
-                              'rotate() | skew() | skewX() | skewY() | ' +
-                              'matrix3d() | translate3d() | translateZ() | scale3d() | scaleZ() | rotate3d()',
-
-      '<unicode-range>': part => /^U\+[0-9a-f?]{1,6}(-[0-9a-f?]{1,6})?\s*$/i.test(part),
-
-      '<unit>': part => part.text === '%' || part in UNITS || lower(part) in UNITS,
-
-      '<uri>': part => part.type === 'uri',
-
-      '<var>': part => {
-        //eslint-disable-next-line no-use-before-define
-        if (part.tokenType === Tokens.USO_VAR) return true;
-        if (part.type !== 'function' || !part.expr) return false;
-        const sp = part.expr.parts;
-        return sp.length && (
-          (sp.length === 1 || sp[1].text === ',') &&
-          (sp[0].type === 'custom-property' && /^var$/i.test(part.name) ||
-           sp[0].type === 'identifier' && /^env$/i.test(part.name))
-        );
-      },
-
-      '<width>': '<length-percentage> | auto',
-    },
-
-    complex: {
-      '<align-content>': 'normal | <baseline-position> | <content-distribution> | ' +
-                         '<aspect-ratio> <content-distribution>? | ' +
-                         '<overflow-position>? <content-position>',
-
-      '<align-self>': 'auto | normal | stretch | <baseline-position> | <overflow-position>? <self-position>',
-
-      '<auto-repeat>': 'repeat( [ auto-fill | auto-fit ] , [ <line-names>? <fixed-size> ]+ <line-names>? )',
-
-      '<auto-track-list>': '[ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>? <auto-repeat> ' +
-                           '[ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>?',
-
-      '<azimuth>': '<angle> | [ [ left-side | far-left | left | center-left | center | center-right | ' +
-                   'right | far-right | right-side ] || behind ] | leftwards | rightwards',
-
-      '<baseline-position>': '[ first | last ]? baseline',
-
-      '<bg-layer>':
-        '<bg-image> || <bg-position> [ / <bg-size> ]? || <repeat-style> || <attachment> || <box>{1,2}',
-
-      '<bg-position>':
-        '[ center | [ left | right ] <length-percentage>? ] && [ center | [ top | bottom ] <length-percentage>? ] | ' +
-        '[ left | center | right | <length-percentage> ] [ top | center | bottom | <length-percentage> ] | ' +
-        '[ left | center | right | top | bottom | <length-percentage> ]',
-
-      '<bg-size>': '[ <length-percentage> | auto ]{1,2} | cover | contain',
-
-      '<border-image-outset>': '[ <length> | <number> ]{1,4}',
-      '<border-image-repeat>': '[ stretch | repeat | round | space ]{1,2}',
-      '<border-image-slice>': Matcher =>
-        // [<number> | <percentage>]{1,4} && fill?
-        // but 'fill' can appear between any of the numbers
-        Matcher.many(
-          [true],
-          Matcher.cast('<nonnegative-number-or-percentage>'),
-          Matcher.cast('<nonnegative-number-or-percentage>'),
-          Matcher.cast('<nonnegative-number-or-percentage>'),
-          Matcher.cast('<nonnegative-number-or-percentage>'),
-          'fill'),
-      '<border-image-width>': '[ <length-percentage> | <number> | auto ]{1,4}',
-      '<border-radius>': '<nonnegative-length-or-percentage>{1,4} [ / <nonnegative-length-or-percentage>{1,4} ]?',
-      '<border-shorthand>': '<border-width> || <border-style> || <color>',
-
-      '<box-shadow>': 'none | <shadow>#',
-
-      '<clip-path>': '<basic-shape> || <geometry-box>',
-
-      '<color>': 'rgb() | rgba() | hsl() | hsla() | hwb() | gray() | device-cmyk() | color() | ' +
-                 '<hex-color> | <named-color>',
-
-      '<color-adjuster>': 'red() | green() | blue() | alpha() | a() | rgb() | hue() | ' +
-                          'saturation() | lightness() | whiteness() | blackness() | ' +
-                          'tint() | shade() | blend() | blenda() | contrast()',
-
-      '<content-list>': '[ <string> | <image> | attr() | content() | counter() | counters() | leader() | ' +
-                        '[ open-quote | close-quote | no-open-quote | no-close-quote ] | ' +
-                        '[ target-counter() | target-counters() | target-text() ] ]+',
-
-      '<counter>': '[ <ident-not-none> <integer>? ]+ | none',
-
-      // "list of comma and/or white space separated <length>s and
-      // <percentage>s".  There is a non-negative constraint.
-      '<dasharray>': Matcher =>
-         Matcher.cast('<nonnegative-length-or-percentage>')
-           .braces(1, Infinity, '#', Matcher.cast(',').question()),
-
-      '<display-listitem>': '<display-outside>? && [ flow | flow-root ]? && list-item',
-
-      '<explicit-track-list>'  : '[ <line-names>? <track-size> ]+ <line-names>?',
-
-      '<family-name>': '<string> | <ident-not-generic-family> <ident>*',
-
-      '<filter-function-list>': '[ <filter-function> | <uri> ]+',
-
-      '<final-bg-layer>':
-        '<color> || <bg-image> || <bg-position> [ / <bg-size> ]? || <repeat-style> || <attachment> || <box>{1,2}',
-
-      '<fixed-repeat>': 'repeat( [ <positive-integer> ] , [ <line-names>? <fixed-size> ]+ <line-names>? )',
-
-      '<fixed-size>': '<fixed-breadth> | ' +
-                      'minmax( <fixed-breadth> , <track-breadth> ) | ' +
-                      'minmax( <inflexible-breadth> , <fixed-breadth> )',
-
-      '<flex-shorthand>': 'none | [ <flex-grow> <flex-shrink>? || <flex-basis> ]',
-
-      '<font-family>': '[ <generic-family> | <family-name> ]#',
-
-      '<font-shorthand>': '[ <font-style> || <font-variant-css21> || <font-weight> || <font-stretch> ]? ' +
-                          '<font-size> [ / <line-height> ]? <font-family>',
-
-      '<font-variant-alternates>': 'stylistic() || historical-forms || styleset() || ' +
-                                   'character-variant() || swash() || ornaments() || annotation()',
-
-      '<font-variant-ligatures>': '[ common-ligatures | no-common-ligatures ] || ' +
-                                  '[ discretionary-ligatures | no-discretionary-ligatures ] || ' +
-                                  '[ historical-ligatures | no-historical-ligatures ] || ' +
-                                  '[ contextual | no-contextual ]',
-
-      '<font-variant-numeric>': '[ lining-nums | oldstyle-nums ] || ' +
-                                '[ proportional-nums | tabular-nums ] || ' +
-                                '[ diagonal-fractions | stacked-fractions ] || ' +
-                                'ordinal || slashed-zero',
-
-      '<font-variant-east-asian>': '[ jis78 | jis83 | jis90 | jis04 | simplified | traditional ] || ' +
-                                   '[ full-width | proportional-width ] || ruby',
-
-      '<font-variant>': '<font-variant-ligatures> || <font-variant-alternates> || <font-variant-caps> || ' +
-                        '<font-variant-numeric> || <font-variant-east-asian>',
-
-      '<grid-auto-columns>': '<track-size>+',
-      '<grid-auto-rows>': '<track-size>+',
-
-      '<grid-line>': 'auto | [ <integer> && <ident-for-grid>? ] | <ident-for-grid> | ' +
-                     '[ span && [ <integer> || <ident-for-grid> ] ]',
-
-      '<grid-template>': 'none | [ <grid-template-rows> / <grid-template-columns> ] | ' +
-                         '[ <line-names>? <string> <track-size>? <line-names>? ]+ ' +
-                         '[ / <explicit-track-list> ]?',
-      '<grid-template-columns>': 'none | <track-list> | <auto-track-list>',
-      '<grid-template-rows>': '<grid-template-columns>',
-
-      '<justify-content>': 'normal | <content-distribution> | <aspect-ratio> <content-distribution>? | ' +
-                           '<overflow-position>? [ <content-position> | left | right ]',
-
-      '<justify-self>': 'auto | normal | stretch | <baseline-position> | <overflow-position>? ' +
-                        '[ <self-position> | left | right ]',
-
-      '<paint>': 'none | child | child() | <color> | ' +
-                 '<uri> [ none | currentColor | <color> ]? | ' +
-                 'context-fill | context-stroke',
-
-      // Because our `alt` combinator is ordered, we need to test these
-      // in order from longest possible match to shortest.
-      '<position>': '[ [ left | right ] <length-percentage> ] && [ [ top | bottom ] <length-percentage> ] | ' +
-                    '[ left | center | right | <length-percentage> ] ' +
-                    '[ top | center | bottom | <length-percentage> ]? | ' +
-                    '[ left | center | right ] || [ top | center | bottom ]',
-
-      '<repeat-style>': 'repeat-x | repeat-y | [ repeat | space | round | no-repeat ]{1,2}',
-
-      '<rgb-color>': '<number>{3} [ / <nonnegative-number-or-percentage> ]? | ' +
-                     '<percentage>{3} [ / <nonnegative-number-or-percentage> ]? | ' +
-                     '<number>#{3} [ , <nonnegative-number-or-percentage> ]? | ' +
-                     '<percentage>#{3} [ , <nonnegative-number-or-percentage> ]?',
-
-      '<hsl-color>': '[ <number> | <angle> ] <percentage>{2} [ / <nonnegative-number-or-percentage> ]? | ' +
-                     '[ <number> | <angle> ] , <percentage>#{2} [ , <nonnegative-number-or-percentage> ]?',
-
-      '<overscroll>': 'contain | none | auto',
-
-      '<shadow>': 'inset? && [ <length>{2,4} && <color>? ]',
-
-      '<single-timing-function>': 'linear | <cubic-bezier-timing-function> | <step-timing-function> | frames()',
-
-      '<text-decoration-line>': 'none | [ underline || overline || line-through || blink ]',
-
-      '<text-emphasis-style>': 'none | ' +
-                               '[ [ filled | open ] || [ dot | circle | double-circle | triangle | sesame ] ] | ' +
-                               '<string>',
-
-      '<track-list>': '[ <line-names>? [ <track-size> | <track-repeat> ] ]+ <line-names>?',
-
-      '<track-repeat>': 'repeat( [ <positive-integer> ] , [ <line-names>? <track-size> ]+ <line-names>? )',
-
-      '<track-size>': '<track-breadth> | minmax( <inflexible-breadth> , <track-breadth> ) | ' +
-                      'fit-content( <length-percentage> )',
-
-      '<transform-origin>': '[ left | center | right | <length-percentage> ] ' +
-                            '[ top | center | bottom | <length-percentage> ] <length>? | ' +
-                            '[ left | center | right | top | bottom | <length-percentage> ] | ' +
-                            '[ [ center | left | right ] && [ center | top | bottom ] ] <length>?',
-
-      '<transition>': '[ none | [ all | <ident> ]# ] || <time> || <single-timing-function> || <time>',
-
-      '<will-change>': 'auto | <animateable-feature>#',
-
-      '<x-one-radius>': '<length-percentage>{1,2}',
-    },
-
-    functions: {
-      'attr': '<ident> [ string | color | url | integer | number | length | angle | time | frequency | <unit> ]? ' +
-              '[ , <attr-fallback> ]?',
-
-      'fit-content': '<length-percentage>',
-
-      'rgb':  '<rgb-color>',
-      'rgba': '<rgb-color>',
-      'hsl':  '<hsl-color>',
-      'hsla': '<hsl-color>',
-      'hwb':  '<hsl-color>',
-      'gray': '<number> [ / <nonnegative-number-or-percentage> ]?',
-      'device-cmyk': '<number-percentage>{4} [ / <nonnegative-number-or-percentage> ]? , <color>?',
-
-      'color':        '[ <color> | [ <number> | <angle> ] ] <color-adjuster>*',
-      'content':      'text | before | after | first-letter | marker',
-      'cubic-bezier': '<number>#{4}',
-      'frames':       '<integer>',
-      'steps':        '<integer> [ , [ start | end ] ]?',
-
-      // used in SVG2 <paint>
-      'child': '<integer>',
-
-      'blur':        '<length>',
-      'brightness':  '<number-percentage>',
-      'contrast':    '<number-percentage>',
-      'drop-shadow': '<length>{2,3} && <color>?',
-      'grayscale':   '<number-percentage>',
-      'hue-rotate':  '<angle-or-0>',
-      'invert':      '<number-percentage>',
-      'opacity':     '<number-percentage>',
-      'saturate':    '<number-percentage>',
-      'sepia':       '<number-percentage>',
-
-      'inset':   '<length-percentage>{1,4} [ round <border-radius> ]?',
-      'circle':  '[ <length-percentage> | closest-side | farthest-side ]? [ at <position> ]?',
-      'ellipse': '[ [ <length-percentage> | closest-side | farthest-side ]{2} ]? [ at <position> ]?',
-      'polygon': '[ [ nonzero | evenodd | inherit ] , ]? [ <length-percentage> <length-percentage> ]#',
-      'rect':    '[ <length> | auto ]#{4}',
-
-      'matrix':     '<number>#{6}',
-      'translate':  '<length-percentage> [ , <length-percentage> ]?',
-      'translateX': '<length-percentage>',
-      'translateY': '<length-percentage>',
-      'scale':      '<number> [ , <number> ]?',
-      'scaleX':     '<number>',
-      'scaleY':     '<number>',
-      'rotate':     '<angle-or-0>',
-      'skew':       '<angle-or-0> [ , <angle-or-0> ]?',
-      'skewX':      '<angle-or-0>',
-      'skewY':      '<angle-or-0>',
-
-      'matrix3d':    '<number>#{16}',
-      'translate3d': '<length-percentage>#{2} , <length>',
-      'translateZ':  '<length>',
-      'scale3d':     '<number>#{3}',
-      'scaleZ':      '<number>',
-      'rotate3d':    '<number>#{3} , <angle-or-0>',
-    },
-
-    functionsMayBeEmpty: new Set([
-      // https://drafts.fxtf.org/filter-effects/#supported-filter-functions
-      // omitted values default to the initial value for interpolation
-      'blur', 'brightness', 'contrast', 'drop-shadow', 'grayscale',
-      'hue-rotate', 'invert', 'opacity', 'saturate', 'sepia',
-      'content',
-    ]),
+  //#endregion
+  //#region Types
+
+  const TYPES = /** @namespace Parser */ {
+    DEFAULT_TYPE: 0,
+    COMBINATOR_TYPE: 1,
+    MEDIA_FEATURE_TYPE: 2,
+    MEDIA_QUERY_TYPE: 3,
+    PROPERTY_NAME_TYPE: 4,
+    PROPERTY_VALUE_TYPE: 5,
+    PROPERTY_VALUE_PART_TYPE: 6,
+    SELECTOR_TYPE: 7,
+    SELECTOR_PART_TYPE: 8,
+    SELECTOR_SUB_PART_TYPE: 9,
+  };
+  const UNITS = {
+    em:   'length',
+    rem:  'length',
+    ex:   'length',
+    px:   'length',
+    cm:   'length',
+    mm:   'length',
+    in:   'length',
+    pt:   'length',
+    pc:   'length',
+    ch:   'length',
+    vh:   'length',
+    vw:   'length',
+    vmax: 'length',
+    vmin: 'length',
+    fr:   'length',
+    q:    'length',
+    deg:  'angle',
+    rad:  'angle',
+    grad: 'angle',
+    turn: 'angle',
+    ms:   'time',
+    s:    'time',
+    hz:   'frequency',
+    khz:  'frequency',
+    dpi:  'resolution',
+    dpcm: 'resolution',
+    dppx: 'resolution',
+    x:    'resolution',
+    ar:   'dimension',
+  };
+  const rxIdentStart = /[-\\_a-zA-Z\u00A0-\uFFFF]+/yu;
+  const rxNameChar = /[-\\_\da-zA-Z\u00A0-\uFFFF]+/yu;
+  const rxUnquotedUrlChar = /[-!#$%&*-[\]-~\u00A0-\uFFFF]+/yu;
+  const rxVendorPrefix = /^-(webkit|moz|ms|o)-(.+)/i;
+  const rxCalc = /^(?:-(webkit|moz|ms|o)-)?(calc|min|max|clamp)\(/i;
+  const lowercaseCache = new Map();
+
+  //#endregion
+  //#region ValidationTypes - definitions
+
+  /** Allowed syntax: text, |, <syntax>, func() */
+  const VTSimple = {
+    '<absolute-size>': 'xx-small | x-small | small | medium | large | x-large | xx-large',
+    '<animateable-feature>': 'scroll-position | contents | <animateable-feature-name>',
+    '<animateable-feature-name>': p => vtIsIdent(p) &&
+      !/^(unset|initial|inherit|will-change|auto|scroll-position|contents)$/i.test(p),
+    '<angle>': p => p.type === 'angle' || p.isCalc,
+    '<angle-or-0>': p => p.text === '0' || p.type === 'angle' || p.isCalc,
+    '<aspect-ratio>': p => p.units && lowerCmp(p.units, 'ar'),
+    '<attr-fallback>': p => !p.isAttr,
+    '<attachment>': 'scroll | fixed | local',
+    '<basic-shape>': 'inset() | circle() | ellipse() | polygon()',
+    '<bg-image>': '<image> | none',
+    '<blend-mode>': 'normal | multiply | screen | overlay | darken | lighten | color-dodge | ' +
+      'color-burn | hard-light | soft-light | difference | exclusion | hue | ' +
+      'saturation | color | luminosity',
+    '<border-style>': 'none | ' +
+      'hidden | dotted | dashed | solid | double | groove | ridge | inset | outset',
+    '<border-width>': '<length> | thin | medium | thick',
+    '<box>': 'padding-box | border-box | content-box',
+    '<clip-source>': '<uri>',
+    '<color>': '<hex-color> | rgb() | rgba() | hsl() | hsla() | hwb() | gray() | ' +
+      'device-cmyk() | color() | <named-color>',
+    '<column-gap>': 'normal | <length-pct>',
+    '<content-distribution>': 'space-between | space-around | space-evenly | stretch',
+    '<content-position>': 'center | start | end | flex-start | flex-end',
+    '<cubic-bezier-timing-function>': 'ease | ease-in | ease-out | ease-in-out | cubic-bezier()',
+    '<display-box>': 'contents | none',
+    '<display-inside>': 'flow | flow-root | table | flex | grid | ruby',
+    '<display-internal>': 'table-row-group | table-header-group | table-footer-group | ' +
+      'table-row | table-cell | table-column-group | table-column | table-caption | ' +
+      'ruby-base | ruby-text | ruby-base-container | ruby-text-container',
+    '<display-legacy>': 'inline-block | inline-table | inline-flex | inline-grid',
+    '<display-outside>': 'block | inline | run-in',
+    '<feature-tag-value>': p => p.type === 'function' && /^[A-Z0-9]{4}$/i.test(p),
+    // custom() isn't actually in the spec
+    '<filter-function>': 'blur() | brightness() | contrast() | custom() | drop-shadow() | ' +
+      'grayscale() | hue-rotate() | invert() | opacity() | saturate() | sepia()',
+    '<flex>': p => p.type === 'grid' && p.value >= 0 || p.isCalc,
+    '<flex-basis>': '<width>',
+    '<flex-direction>': 'row | row-reverse | column | column-reverse',
+    '<flex-grow>': '<number>',
+    '<flex-shrink>': '<number>',
+    '<flex-wrap>': 'nowrap | wrap | wrap-reverse',
+    '<font-size>': '<absolute-size> | <relative-size> | <length-pct>',
+    '<font-stretch>': '<font-stretch-named> | <percentage>',
+    '<font-stretch-named>': 'normal | ultra-condensed | extra-condensed | condensed | ' +
+      'semi-condensed | semi-expanded | expanded | extra-expanded | ultra-expanded',
+    '<font-variant-caps>':
+      'small-caps | all-small-caps | petite-caps | all-petite-caps | unicase | titling-caps',
+    '<font-variant-css21>': 'normal | small-caps',
+    '<font-weight>': 'normal | bold | bolder | lighter | <number>',
+    '<generic-family>': 'serif | sans-serif | cursive | fantasy | monospace | system-ui | ' +
+      'emoji | math | fangsong | ui-serif | ui-sans-serif | ui-monospace | ui-rounded',
+    '<geometry-box>': '<shape-box> | fill-box | stroke-box | view-box',
+    '<glyph-angle>': p => p.type === 'angle' && p.units === 'deg',
+    '<gradient>': p =>
+      p.type === 'function' &&
+      /^(?:-(?:webkit|moz|ms|o)-)?(?:repeating-)?(?:radial-|linear-|conic-)?gradient/i.test(p),
+    '<hex-color>': p => p.tokenType === Tokens.HASH, //eslint-disable-line no-use-before-define
+    '<icccolor>': 'cielab() | cielch() | cielchab() | icc-color() | icc-named-color()',
+    '<ident>': vtIsIdent,
+    '<ident-for-grid>': p => vtIsIdent(p) &&
+      !/^(span|auto|initial|inherit|unset|default)$/i.test(p.value),
+    '<ident-not-generic-family>': p => vtIsIdent(p) && !VTSimple['<generic-family>'](p),
+    '<ident-not-none>': p => vtIsIdent(p) && !lowerCmp(p.value, 'none'),
+    '<image>': '<uri> | <gradient> | cross-fade()',
+    '<inflexible-breadth>': '<length-pct> | min-content | max-content | auto',
+    '<integer>': p => p.isInt || p.isCalc,
+    '<length>': vtIsLength,
+    '<length-pct>': p => vtIsLength(p) || vtIsPct(p),
+    '<line>': p => p.isInt,
+    '<line-height>': '<number> | <length-pct> | normal',
+    '<line-names>': p =>
+      p.tokenType === Tokens.LBRACKET && // eslint-disable-line no-use-before-define
+      p.text.endsWith(']') && (
+        !p.expr ||
+        !p.expr.parts.length ||
+        p.expr.parts.every(VTSimple['<ident-for-grid>'], VTSimple)
+      ),
+    '<miterlimit>': p => p.type === 'number' && p.value >= 1 || p.isCalc,
+    '<nonnegative-len-pct>': p =>
+      p.value >= 0 && (p.type === 'percentage' || vtIsLength(p)) || p.isCalc,
+    '<nonnegative-num-pct>': p =>
+      p.value >= 0 && (p.type === 'number' || p.type === 'percentage') || p.isCalc,
+    //eslint-disable-next-line no-use-before-define
+    '<named-color>': p => p.text in Colors || lower(p.text) in Colors,
+    '<number>': p => p.type === 'number' || p.isCalc,
+    '<number-pct>': p => p.type === 'number' || p.type === 'percentage' || p.isCalc,
+    '<opacity-value>': p => p.type === 'number' && p.value >= 0 && p.value <= 1 || p.isCalc,
+    '<overflow>': 'visible | hidden | clip | scroll | auto',
+    '<overflow-position>': 'unsafe | safe',
+    '<percentage>': vtIsPct,
+    '<positive-integer>': p => p.isInt && p.value > 0 || p.isCalc,
+    '<relative-size>': 'smaller | larger',
+    '<row-gap>': '<column-gap>',
+    '<self-position>': 'center | start | end | self-start | self-end | flex-start | flex-end',
+    '<shape-box>': '<box> | margin-box',
+    '<single-animation-direction>': 'normal | reverse | alternate | alternate-reverse',
+    '<single-animation-fill-mode>': 'none | forwards | backwards | both',
+    '<single-animation-name>': p => vtIsIdent(p) &&
+      /^(?!(none|unset|initial|inherit)$)-?[a-z_][-a-z0-9_]+$/i.test(p),
+    '<step-timing-function>': 'step-start | step-end | steps()',
+    '<string>': p => p.type === 'string',
+    '<text-align>': 'start | end | left | right | center | justify | match-parent',
+    '<text-decoration-style>': 'solid | double | dotted | dashed | wavy',
+    '<time>': p => p.type === 'time',
+    '<track-breadth>': '<length-pct> | <flex> | min-content | max-content | auto',
+    '<transform-function>': 'matrix() | translate() | translateX() | translateY() | ' +
+      'scale() | scaleX() | scaleY() | ' +
+      'rotate() | skew() | skewX() | skewY() | ' +
+      'matrix3d() | translate3d() | translateZ() | scale3d() | scaleZ() | rotate3d()',
+    '<unicode-range>': p => /^U\+[0-9a-f?]{1,6}(-[0-9a-f?]{1,6})?\s*$/i.test(p),
+    '<unit>': p => p.text === '%' || p in UNITS || lower(p) in UNITS,
+    '<uri>': p => p.type === 'uri',
+    '<width>': p => vtIsLength(p) || vtIsPct(p) || lowerCmp(p.text, 'auto'),
+    '<width-height>': '<length-pct> | min-content | max-content | fit-content() | ' +
+      '-moz-available | -webkit-fill-available',
   };
 
-  //endregion
-  //region Colors
+  const VTComplex = {
+    '<align-content>': 'normal | <baseline-position> | <content-distribution> | ' +
+      '<aspect-ratio> <content-distribution>? | <overflow-position>? <content-position>',
+    '<align-self>':
+      'auto | normal | stretch | <baseline-position> | <overflow-position>? <self-position>',
+    '<auto-repeat>':
+      'repeat( [ auto-fill | auto-fit ] , [ <line-names>? <fixed-size> ]+ <line-names>? )',
+    '<auto-track-list>':
+      '[ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>? <auto-repeat> ' +
+      '[ <line-names>? [ <fixed-size> | <fixed-repeat> ] ]* <line-names>?',
+    '<azimuth>':
+      '<angle> | [ [ left-side | far-left | left | center-left | center | center-right | ' +
+      'right | far-right | right-side ] || behind ] | leftwards | rightwards',
+    '<baseline-position>': '[ first | last ]? baseline',
+    '<bg-layer>':
+      '<bg-image> || <bg-position> [ / <bg-size> ]? || <repeat-style> || <attachment> || <box>{1,2}',
+    '<bg-position>':
+      '[ center | [ left | right ] <length-pct>? ] && [ center | [ top | bottom ] <length-pct>? ] | ' +
+      '[ left | center | right | <length-pct> ] [ top | center | bottom | <length-pct> ] | ' +
+      '[ left | center | right | top | bottom | <length-pct> ]',
+    '<bg-size>': '[ <length-pct> | auto ]{1,2} | cover | contain',
+    '<border-image-outset>': '[ <length> | <number> ]{1,4}',
+    '<border-image-repeat>': '[ stretch | repeat | round | space ]{1,2}',
+    '<border-image-slice>': Matcher =>
+      // [<number> | <percentage>]{1,4} && fill?
+      // but 'fill' can appear between any of the numbers
+      Matcher.many(
+        [true],
+        Matcher.parse('<nonnegative-num-pct>'),
+        Matcher.parse('<nonnegative-num-pct>'),
+        Matcher.parse('<nonnegative-num-pct>'),
+        Matcher.parse('<nonnegative-num-pct>'),
+        'fill'),
+    '<border-image-width>': '[ <length-pct> | <number> | auto ]{1,4}',
+    '<border-radius>': '<nonnegative-len-pct>{1,4} [ / <nonnegative-len-pct>{1,4} ]?',
+    '<border-shorthand>': '<border-width> || <border-style> || <color>',
+    '<box-shadow>': 'none | <shadow>#',
+    '<clip-path>': '<basic-shape> || <geometry-box>',
+    '<color-adjuster>':
+      'red() | green() | blue() | alpha() | a() | rgb() | hue() | saturation() | lightness() | ' +
+      'whiteness() | blackness() | tint() | shade() | blend() | blenda() | contrast()',
+    '<content-list>':
+      '[ <string> | <image> | attr() | content() | counter() | counters() | leader() | ' +
+      '[ open-quote | close-quote | no-open-quote | no-close-quote ] | ' +
+      '[ target-counter() | target-counters() | target-text() ] ]+',
+    '<counter>': '[ <ident-not-none> <integer>? ]+ | none',
+    '<dasharray>': Matcher =>
+      Matcher.parse('<nonnegative-len-pct>')
+        .braces(1, Infinity, '#', Matcher.parse(',').braces(0, 1, '?')),
+    '<display-listitem>': '<display-outside>? && [ flow | flow-root ]? && list-item',
+    '<explicit-track-list>': '[ <line-names>? <track-size> ]+ <line-names>?',
+    '<family-name>': '<string> | <ident-not-generic-family> <ident>*',
+    '<filter-function-list>': '[ <filter-function> | <uri> ]+',
+    '<final-bg-layer>': '<color> || <bg-image> || <bg-position> [ / <bg-size> ]? || ' +
+      '<repeat-style> || <attachment> || <box>{1,2}',
+    '<fixed-repeat>':
+      'repeat( [ <positive-integer> ] , [ <line-names>? <fixed-size> ]+ <line-names>? )',
+    '<fixed-size>': '<length-pct> | ' +
+      'minmax( <length-pct> , <track-breadth> ) | ' +
+      'minmax( <inflexible-breadth> , <length-pct> )',
+    '<flex-shorthand>': 'none | [ <flex-grow> <flex-shrink>? || <flex-basis> ]',
+    '<font-family>': '[ <generic-family> | <family-name> ]#',
+    '<font-style>': 'normal | italic | oblique <angle>?',
+    '<font-short-core>': '<font-size> [ / <line-height> ]? <font-family>',
+    '<font-short-tweak-no-pct>':
+      '<font-style> || <font-variant-css21> || <font-weight> || <font-stretch-named>',
+    '<font-variant-alternates>': 'stylistic() || historical-forms || styleset() || ' +
+      'character-variant() || swash() || ornaments() || annotation()',
+    '<font-variant-ligatures>': '[ common-ligatures | no-common-ligatures ] || ' +
+      '[ discretionary-ligatures | no-discretionary-ligatures ] || ' +
+      '[ historical-ligatures | no-historical-ligatures ] || ' +
+      '[ contextual | no-contextual ]',
+    '<font-variant-numeric>': '[ lining-nums | oldstyle-nums ] || ' +
+      '[ proportional-nums | tabular-nums ] || ' +
+      '[ diagonal-fractions | stacked-fractions ] || ' +
+      'ordinal || slashed-zero',
+    '<font-variant-east-asian>': '[ jis78 | jis83 | jis90 | jis04 | simplified | traditional ] || ' +
+      '[ full-width | proportional-width ] || ruby',
+    '<font-variant>': '<font-variant-ligatures> || <font-variant-alternates> || <font-variant-caps> || ' +
+      '<font-variant-numeric> || <font-variant-east-asian>',
+    '<grid-auto-columns>': '<track-size>+',
+    '<grid-auto-rows>': '<track-size>+',
+    '<grid-line>': 'auto | [ <integer> && <ident-for-grid>? ] | <ident-for-grid> | ' +
+      '[ span && [ <integer> || <ident-for-grid> ] ]',
+    '<grid-template>': 'none | [ <grid-template-rows> / <grid-template-columns> ] | ' +
+      '[ <line-names>? <string> <track-size>? <line-names>? ]+ ' +
+      '[ / <explicit-track-list> ]?',
+    '<grid-template-columns>': 'none | <track-list> | <auto-track-list>',
+    '<grid-template-rows>': '<grid-template-columns>',
+    '<hsl-color>': '[ <number> | <angle> ] <percentage>{2} [ / <nonnegative-num-pct> ]? | ' +
+      '[ <number> | <angle> ] , <percentage>#{2} [ , <nonnegative-num-pct> ]?',
+    '<justify-content>': 'normal | <content-distribution> | <aspect-ratio> <content-distribution>? | ' +
+      '<overflow-position>? [ <content-position> | left | right ]',
+    '<justify-self>': 'auto | normal | stretch | <baseline-position> | <overflow-position>? ' +
+      '[ <self-position> | left | right ]',
+    '<overscroll>': 'contain | none | auto',
+    '<paint>': 'none | child | child() | <color> | ' +
+      '<uri> [ none | currentColor | <color> ]? | ' +
+      'context-fill | context-stroke',
+    // Because our `alt` combinator is ordered, we need to test these
+    // in order from longest possible match to shortest.
+    '<position>':
+      '[ [ left | right ] <length-pct> ] && [ [ top | bottom ] <length-percentagepct ] | ' +
+      '[ left | center | right | <length-pct> ] ' +
+      '[ top | center | bottom | <length-pct> ]? | ' +
+      '[ left | center | right ] || [ top | center | bottom ]',
+    '<repeat-style>': 'repeat-x | repeat-y | [ repeat | space | round | no-repeat ]{1,2}',
+    '<rgb-color>':
+      '[ <number>{3} | <percentage>{3} ] [ / <nonnegative-num-pct> ]? | ' +
+      '[ <number>#{3} | <percentage>#{3} ] [ , <nonnegative-num-pct> ]?',
+    '<shadow>': 'inset? && [ <length>{2,4} && <color>? ]',
+    '<single-timing-function>': 'linear | <cubic-bezier-timing-function> | <step-timing-function> | frames()',
+    '<text-decoration-line>': 'none | [ underline || overline || line-through || blink ]',
+    '<text-emphasis-style>': 'none | ' +
+      '[ [ filled | open ] || [ dot | circle | double-circle | triangle | sesame ] ] | ' +
+      '<string>',
+    '<track-list>': '[ <line-names>? [ <track-size> | <track-repeat> ] ]+ <line-names>?',
+    '<track-repeat>': 'repeat( [ <positive-integer> ] , [ <line-names>? <track-size> ]+ <line-names>? )',
+    '<track-size>': '<track-breadth> | minmax( <inflexible-breadth> , <track-breadth> ) | ' +
+      'fit-content( <length-pct> )',
+    '<transform-origin>': '[ left | center | right | <length-pct> ] ' +
+      '[ top | center | bottom | <length-pct> ] <length>? | ' +
+      '[ left | center | right | top | bottom | <length-pct> ] | ' +
+      '[ [ center | left | right ] && [ center | top | bottom ] ] <length>?',
+    '<transition>': '[ none | [ all | <ident> ]# ] || <time> || <single-timing-function> || <time>',
+    '<will-change>': 'auto | <animateable-feature>#',
+    '<x-one-radius>': '<length-pct>{1,2}',
+  };
+
+  const VTFunctions = {
+    'attr': '<ident> ' +
+      '[ string | color | url | integer | number | length | angle | time | frequency | <unit> ]? ' +
+      '[ , <attr-fallback> ]?',
+    'fit-content': '<length-pct>',
+
+    'rgb':  '<rgb-color>',
+    'rgba': '<rgb-color>',
+    'hsl':  '<hsl-color>',
+    'hsla': '<hsl-color>',
+    'hwb':  '<hsl-color>',
+    'gray': '<number> [ / <nonnegative-num-pct> ]?',
+    'device-cmyk': '<number-pct>{4} [ / <nonnegative-num-pct> ]? , <color>?',
+
+    'color':        '[ <color> | [ <number> | <angle> ] ] <color-adjuster>*',
+    'content':      'text | before | after | first-letter | marker',
+    'cubic-bezier': '<number>#{4}',
+    'frames':       '<integer>',
+    'steps':        '<integer> [ , [ start | end ] ]?',
+
+    // used in SVG2 <paint>
+    'child': '<integer>',
+
+    'blur':        '<length>',
+    'brightness':  '<number-pct>',
+    'contrast':    '<number-pct>',
+    'drop-shadow': '<length>{2,3} && <color>?',
+    'grayscale':   '<number-pct>',
+    'hue-rotate':  '<angle-or-0>',
+    'invert':      '<number-pct>',
+    'opacity':     '<number-pct>',
+    'saturate':    '<number-pct>',
+    'sepia':       '<number-pct>',
+
+    'inset':   '<length-pct>{1,4} [ round <border-radius> ]?',
+    'circle':  '[ <length-pct> | closest-side | farthest-side ]? [ at <position> ]?',
+    'ellipse': '[ [ <length-pct> | closest-side | farthest-side ]{2} ]? [ at <position> ]?',
+    'polygon': '[ [ nonzero | evenodd | inherit ] , ]? [ <length-pct> <length-pct> ]#',
+    'rect':    '[ <length> | auto ]#{4}',
+
+    'matrix':     '<number>#{6}',
+    'translate':  '<length-pct> [ , <length-pct> ]?',
+    'translateX': '<length-pct>',
+    'translateY': '<length-pct>',
+    'scale':      '<number> [ , <number> ]?',
+    'scaleX':     '<number>',
+    'scaleY':     '<number>',
+    'rotate':     '<angle-or-0>',
+    'skew':       '<angle-or-0> [ , <angle-or-0> ]?',
+    'skewX':      '<angle-or-0>',
+    'skewY':      '<angle-or-0>',
+
+    'matrix3d':    '<number>#{16}',
+    'translate3d': '<length-pct>#{2} , <length>',
+    'translateZ':  '<length>',
+    'scale3d':     '<number>#{3}',
+    'scaleZ':      '<number>',
+    'rotate3d':    '<number>#{3} , <angle-or-0>',
+  };
+
+  const VTFunctionsMayBeEmpty = new Set([
+    // https://drafts.fxtf.org/filter-effects/#supported-filter-functions
+    // omitted values default to the initial value for interpolation
+    'blur',
+    'brightness',
+    'content',
+    'contrast',
+    'drop-shadow',
+    'grayscale',
+    'hue-rotate',
+    'invert',
+    'opacity',
+    'saturate',
+    'sepia',
+  ]);
+
+  //#endregion
+  //#region Colors
 
   const Colors = {
     aliceblue:            '#f0f8ff',
@@ -1399,144 +1214,108 @@ self.parserlib = (() => {
     visitedtext: '',
   };
 
-  //endregion
-  //region Tokens
+  //#endregion
+  //#region Tokens
 
-  /*
-   * The following token names are defined in CSS3 Grammar:
-   * https://www.w3.org/TR/css3-syntax/#lexical
-   */
+  /* https://www.w3.org/TR/css3-syntax/#lexical */
   const Tokens = Object.assign([], {
     EOF: {}, // must be the first token
   }, {
     // HTML-style comments
-    CDO: {},
     CDC: {},
-
+    CDO: {},
     // ignorables
-    S: {whitespace: true},
-    COMMENT: {whitespace: true, comment: true, hide: true},
-
+    COMMENT: {hide: true},
+    S: {},
     // attribute equality
-    INCLUDES: {text: '~='},
     DASHMATCH: {text: '|='},
+    INCLUDES: {text: '~='},
     PREFIXMATCH: {text: '^='},
-    SUFFIXMATCH: {text: '$='},
     SUBSTRINGMATCH: {text: '*='},
-
+    SUFFIXMATCH: {text: '$='},
     // identifier types
-    STRING: {},
-    IDENT: {},
     HASH: {},
-
+    IDENT: {},
+    STRING: {},
     // at-keywords
-    IMPORT_SYM: {text: '@import'},
-    PAGE_SYM: {text: '@page'},
-    MEDIA_SYM: {text: '@media'},
-    FONT_FACE_SYM: {text: '@font-face'},
     CHARSET_SYM: {text: '@charset'},
-    NAMESPACE_SYM: {text: '@namespace'},
-    SUPPORTS_SYM: {text: '@supports'},
-    VIEWPORT_SYM: {text: ['@viewport', '@-ms-viewport', '@-o-viewport']},
     DOCUMENT_SYM: {text: ['@document', '@-moz-document']},
-    UNKNOWN_SYM: {}, //{ name: "ATKEYWORD"},
-
-    // CSS3 animations
+    FONT_FACE_SYM: {text: '@font-face'},
+    IMPORT_SYM: {text: '@import'},
     KEYFRAMES_SYM: {text: ['@keyframes', '@-webkit-keyframes', '@-moz-keyframes', '@-o-keyframes']},
-
-    // important symbol
-    IMPORTANT_SYM: {},
-
+    MEDIA_SYM: {text: '@media'},
+    NAMESPACE_SYM: {text: '@namespace'},
+    PAGE_SYM: {text: '@page'},
+    SUPPORTS_SYM: {text: '@supports'},
+    UNKNOWN_SYM: {},
+    VIEWPORT_SYM: {text: ['@viewport', '@-ms-viewport', '@-o-viewport']},
     // measurements
-    LENGTH: {},
     ANGLE: {},
-    TIME: {},
-    FREQ: {},
     DIMENSION: {},
-    PERCENTAGE: {},
+    FREQ: {},
+    LENGTH: {},
     NUMBER: {},
-
+    PERCENTAGE: {},
+    TIME: {},
     // functions
-    URI: {},
     FUNCTION: {},
-
+    URI: {},
     // Unicode ranges
     UNICODE_RANGE: {},
-
-    /*
-     * The following token names are defined in CSS3 Selectors: https://www.w3.org/TR/css3-selectors/#selector-syntax
-     */
-
     // invalid string
     INVALID: {},
-
     // combinators
-    PLUS: {text: '+'},
-    GREATER: {text: '>'},
-    COMMA: {text: ','},
-    TILDE: {text: '~'},
     COLUMN: {text: '||'},
-
+    COMMA: {text: ','},
+    GREATER: {text: '>'},
+    PLUS: {text: '+'},
+    TILDE: {text: '~'},
     // modifier
-    NOT: {},
     ANY: {text: ['any', '-webkit-any', '-moz-any']},
     IS: {},
+    NOT: {},
     WHERE: {},
-
-    /*
-     * Defined in CSS3 Paged Media
-     */
-    TOPLEFTCORNER_SYM: {text: '@top-left-corner'},
-    TOPLEFT_SYM: {text: '@top-left'},
-    TOPCENTER_SYM: {text: '@top-center'},
-    TOPRIGHT_SYM: {text: '@top-right'},
-    TOPRIGHTCORNER_SYM: {text: '@top-right-corner'},
+    // CSS3 Paged Media
+    BOTTOMCENTER_SYM: {text: '@bottom-center'},
     BOTTOMLEFTCORNER_SYM: {text: '@bottom-left-corner'},
     BOTTOMLEFT_SYM: {text: '@bottom-left'},
-    BOTTOMCENTER_SYM: {text: '@bottom-center'},
-    BOTTOMRIGHT_SYM: {text: '@bottom-right'},
     BOTTOMRIGHTCORNER_SYM: {text: '@bottom-right-corner'},
-    LEFTTOP_SYM: {text: '@left-top'},
-    LEFTMIDDLE_SYM: {text: '@left-middle'},
+    BOTTOMRIGHT_SYM: {text: '@bottom-right'},
     LEFTBOTTOM_SYM: {text: '@left-bottom'},
-    RIGHTTOP_SYM: {text: '@right-top'},
-    RIGHTMIDDLE_SYM: {text: '@right-middle'},
+    LEFTMIDDLE_SYM: {text: '@left-middle'},
+    LEFTTOP_SYM: {text: '@left-top'},
     RIGHTBOTTOM_SYM: {text: '@right-bottom'},
-
-    /*
-     * The following token names are defined in CSS3 Media Queries: https://www.w3.org/TR/css3-mediaqueries/#syntax
-     */
+    RIGHTMIDDLE_SYM: {text: '@right-middle'},
+    RIGHTTOP_SYM: {text: '@right-top'},
+    TOPCENTER_SYM: {text: '@top-center'},
+    TOPLEFTCORNER_SYM: {text: '@top-left-corner'},
+    TOPLEFT_SYM: {text: '@top-left'},
+    TOPRIGHTCORNER_SYM: {text: '@top-right-corner'},
+    TOPRIGHT_SYM: {text: '@top-right'},
+    /* CSS3 Media Queries */
     RESOLUTION: {state: 'media'},
-
     /*
-     * The following token names are not defined in any CSS specification but are used by the lexer.
+     * The following token names are not defined in any CSS specification.
      */
-
-    // not a real token, but useful for stupid IE filters
-    IE_FUNCTION: {},
-
-    // part of CSS3 grammar but not the Flex code
     CHAR: {},
-
-    // Not defined as tokens, but might as well be
-    PIPE: {text: '|'},
-    SLASH: {text: '/'},
-    MINUS: {text: '-'},
-    STAR: {text: '*'},
-
-    LBRACE: {text: '{', endChar: '}'},
-    RBRACE: {text: '}'},
-    LBRACKET: {text: '[', endChar: ']'},
-    RBRACKET: {text: ']'},
-    EQUALS: {text: '='},
     COLON: {text: ':'},
-    SEMICOLON: {text: ';'},
-    LPAREN: {text: '(', endChar: ')'},
-    RPAREN: {text: ')'},
-    DOT: {text: '.'},
-
-    USO_VAR: {comment: true},
     CUSTOM_PROP: {},
+    DOT: {text: '.'},
+    EQUALS: {text: '='},
+    IE_FUNCTION: {},
+    IMPORTANT: {},
+    LBRACE: {text: '{', endChar: '}'},
+    LBRACKET: {text: '[', endChar: ']'},
+    LPAREN: {text: '(', endChar: ')'},
+    MINUS: {text: '-'},
+    PIPE: {text: '|'},
+    RBRACE: {text: '}'},
+    RBRACKET: {text: ']'},
+    RPAREN: {text: ')'},
+    SEMICOLON: {text: ';'},
+    SLASH: {text: '/'},
+    STAR: {text: '*'},
+    USO_VAR: {},
   });
   // make Tokens an array of tokens, store the index in original prop, add 'name' to each token
   const typeMap = new Map();
@@ -1553,7 +1332,7 @@ self.parserlib = (() => {
   }
   Tokens.UNKNOWN = -1;
   Tokens.name = index => (Tokens[index] || {}).name;
-  Tokens.type = text => typeMap.get(text) || -1;
+  Tokens.type = text => typeMap.get(text) || Tokens.UNKNOWN;
 
   const TT = {
     attrMatch: [
@@ -1635,14 +1414,18 @@ self.parserlib = (() => {
       Tokens.STAR,
       Tokens.MINUS,
     ],
-    ns: [
-      Tokens.IDENT,
-      Tokens.STAR,
-    ],
     plusMinus: [
       Tokens.MINUS,
       Tokens.PLUS,
     ],
+    pseudo: [
+      Tokens.FUNCTION,
+      Tokens.IDENT,
+    ],
+    semiS: [
+      Tokens.SEMICOLON,
+      Tokens.S,
+    ],
     stringUri: [
       Tokens.STRING,
       Tokens.URI,
@@ -1671,26 +1454,8 @@ self.parserlib = (() => {
     Tokens.CUSTOM_PROP,
   ];
 
-  //endregion
-  //region lowerCase helper
-
-  const lowercaseCache = new Map();
-
-  function lower(text) {
-    if (typeof text !== 'string') text = `${text}`;
-    let result = lowercaseCache.get(text);
-    if (result) return result;
-    result = text.toLowerCase();
-    lowercaseCache.set(text, result);
-    return result;
-  }
-
-  function lowerCmp(a, b) {
-    return a.length === b.length && (a === b || lower(a) === lower(b));
-  }
-
-  //endregion
-  //region StringReader
+  //#endregion
+  //#region StringReader
 
   class StringReader {
 
@@ -1709,6 +1474,10 @@ self.parserlib = (() => {
       return this._input[this._cursor + count - 1] || null;
     }
 
+    peekTest(stickyRx) {
+      return stickyTest(stickyRx, this._cursor, this._input);
+    }
+
     read() {
       const c = this._input[this._cursor];
       if (!c) return null;
@@ -1747,7 +1516,7 @@ self.parserlib = (() => {
      */
     readTo(pattern) {
       const i = this._input.indexOf(pattern, this._cursor);
-      if (i < 0) throw new Error(`Expected ${pattern}' at line ${this._line}, col ${this._col}.`);
+      if (i < 0) throw new Error(`Expected '${pattern}'.`);
       return this.readCount(i - this._cursor + pattern.length);
     }
 
@@ -1759,8 +1528,7 @@ self.parserlib = (() => {
      */
     readMatch(matcher) {
       if (matcher.sticky) {
-        matcher.lastIndex = this._cursor;
-        return matcher.test(this._input) ?
+        return stickyTest(matcher, this._cursor, this._input) ?
           this.readCount(RegExp.lastMatch.length) :
           null;
       }
@@ -1787,26 +1555,23 @@ self.parserlib = (() => {
       const len = this._input.length;
       if (this._cursor >= len) return null;
       if (!count) return '';
-
       const text = this._input.substr(this._cursor, count);
       this._cursor = Math.min(this._cursor + count, len);
-
       let prev = -1;
       for (let i = 0; (i = text.indexOf('\n', i)) >= 0; prev = i, i++) this._line++;
       this._col = prev < 0 ? this._col + count : count - prev;
-
       return text;
     }
   }
 
-  //endregion
-  //region Matcher
+  //#endregion
+  //#region Matcher
 
   /**
    * Reuses a Matcher for a ValidationTypes definition string instead of reparsing it.
    * @type {Map<string, Matcher>}
    */
-  const cachedMatcher = new Map();
+  const matcherCache = new Map();
 
   /**
    * This class implements a combinator library for matcher functions.
@@ -1820,11 +1585,27 @@ self.parserlib = (() => {
       if (options) this.options = options;
     }
 
+    /**
+     * @param {PropertyValueIterator} e
+     * @return {?boolean}
+     */
+    match(e) {
+      return e.popMark(this.matchFunc(e.mark()));
+    }
+
+    braces(min, max, marker, sep) {
+      return new Matcher(Matcher.funcBraces, Matcher.toStringBraces, {
+        min, max, marker,
+        sep: sep && Matcher.seq(sep, this),
+        embraced: this,
+      });
+    }
+
     static parse(str) {
-      let m = cachedMatcher.get(str);
+      let m = matcherCache.get(str);
       if (m) return m;
       m = Matcher.doParse(str);
-      cachedMatcher.set(str, m);
+      matcherCache.set(str, m);
       return m;
     }
 
@@ -1833,7 +1614,8 @@ self.parserlib = (() => {
       const reader = new StringReader(str);
       const result = Matcher.parseGrammar(reader);
       if (!reader.eof()) {
-        throw new Error(`Internal error. Expected end of string ${reader._line}:${reader._col}.`);
+        throw new Error('Internal grammar error. ' +
+          `Expected end of string at ${reader._cursor}: ${reader._input}.`);
       }
       return result;
     }
@@ -1844,10 +1626,10 @@ self.parserlib = (() => {
 
     // Matcher for a single type.
     static fromType(type) {
-      let m = cachedMatcher.get(type);
+      let m = matcherCache.get(type);
       if (m) return m;
-      m = new Matcher(Matcher.matchFunc.fromType, type, type);
-      cachedMatcher.set(type, m);
+      m = new Matcher(Matcher.funcFromType, type, type);
+      matcherCache.set(type, m);
       return m;
     }
 
@@ -1855,14 +1637,14 @@ self.parserlib = (() => {
     static seq(...args) {
       const ms = args.map(Matcher.cast);
       if (ms.length === 1) return ms[0];
-      return new Matcher(Matcher.matchFunc.seq, Matcher.toStringFunc.seq, ms);
+      return new Matcher(Matcher.funcSeq, Matcher.toStringSeq, ms);
     }
 
     // Matcher for one or more alternatives, where exactly one must occur.
     static alt(...args) {
       const ms = args.map(Matcher.cast);
       if (ms.length === 1) return ms[0];
-      return new Matcher(Matcher.matchFunc.alt, Matcher.toStringFunc.alt, ms);
+      return new Matcher(Matcher.funcAlt, Matcher.toStringAlt, ms);
     }
 
     /**
@@ -1872,117 +1654,55 @@ self.parserlib = (() => {
      * maximize the number of items matched.
      */
     static many(required, ...args) {
-      const ms = [];
-      for (const arg of args) {
-        if (arg.expand) {
-          ms.push(...ValidationTypes.complex[arg.expand].options);
-        } else {
-          ms.push(Matcher.cast(arg));
-        }
-      }
-      const m = new Matcher(Matcher.matchFunc.many, Matcher.toStringFunc.many, ms);
-      m.required = required === true ? new Array(ms.length).fill(true) : required;
+      const ms = args.map(Matcher.cast);
+      const m = new Matcher(Matcher.funcMany, Matcher.toStringMany, ms);
+      m.required = required === true ? Array(ms.length).fill(true) : required;
       return m;
     }
 
-    // Matcher for two or more options in any order, all mandatory.
-    static andand(...args) {
-      return Matcher.many(true, ...args);
-    }
+    /**************************** matchFunc **********************/
 
-    // Matcher for two or more options in any order, at least one must be present.
-    static oror(...args) {
-      return Matcher.many(false, ...args);
+    /**
+     * @this {Matcher}
+     * @param {PropertyValueIterator} expr
+     */
+    static funcAlt(expr) {
+      return this.options.some(Matcher.invoke, expr);
     }
     /**
-     * @param {PropertyValueIterator} e
-     * @return {?boolean}
+     * @this {Matcher}
+     * @param {PropertyValueIterator} expr
      */
-    match(e) {
-      return e.popMark(this.matchFunc(e.mark()));
-    }
-
-    // Basic combinators
-
-    then(m) {
-      return Matcher.seq(this, m);
-    }
-
-    or(m) {
-      return Matcher.alt(this, m);
-    }
-
-    andand(m) {
-      return Matcher.many(true, this, m);
-    }
-
-    oror(m) {
-      return Matcher.many(false, this, m);
-    }
-
-    // Component value multipliers
-    star() {
-      return this.braces(0, Infinity, '*');
-    }
-
-    plus() {
-      return this.braces(1, Infinity, '+');
-    }
-
-    question() {
-      return this.braces(0, 1, '?');
-    }
-
-    hash() {
-      return this.braces(1, Infinity, '#', Matcher.cast(','));
-    }
-
-    braces(min, max, marker, optSep) {
-      if (optSep) {
-        optSep = optSep.then(this);
+    static funcBraces(expr) {
+      const {min, max, sep, embraced} = this.options;
+      let i = 0;
+      while (i < max && (i && sep || embraced).match(expr)) {
+        i++;
       }
-      if (!marker || marker === '#') {
-        marker = `${marker || ''}{${min}${min === max ? '' : ',' + max}}`;
-      }
-      const bracesMatch = expression => {
-        let i = 0;
-        while (i < max && (i && optSep || this).match(expression)) {
-          i++;
-        }
-        return i >= min;
-      };
-      const bracesToString = () =>
-        this.toString(Matcher.prec.MOD) + marker;
-      return new Matcher(bracesMatch, bracesToString);
+      return i >= min;
     }
-  }
-
-  // Precedence table of combinators.
-  Matcher.prec = {
-    MOD: 5,
-    SEQ: 4,
-    ANDAND: 3,
-    OROR: 2,
-    ALT: 1,
-  };
-
-  Matcher.matchFunc = {
-
-    alt(expression) {
-      return this.options.some(m => m.match(expression));
-    },
-
-    fromType(expr) {
-      return expr.hasNext() && ValidationTypes.isType(expr, this.options);
-    },
-
-    seq(expression) {
-      return this.options.every(m => m.match(expression));
-    },
-
-    many(expression) {
+    /**
+     * @this {Matcher}
+     * @param {PropertyValueIterator} expr
+     */
+    static funcFromType(expr) {
+      return expr.hasNext &&
+        vtIsType(expr, this.options);
+    }
+    /**
+     * @this {PropertyValueIterator}
+     * @param {Matcher} m
+     */
+    static invoke(m) {
+      return m.match(this);
+    }
+    /**
+     * @this {Matcher}
+     * @param {PropertyValueIterator} expr
+     */
+    static funcMany(expr) {
       const seen = [];
-      const {options: ms, required} = this;
+      const {/** @type {Matcher[]} */options: ms, required} = this;
       let max = 0;
       let pass = 0;
       // If couldn't get a complete match, retrace our steps to make the
@@ -2001,25 +1721,24 @@ self.parserlib = (() => {
         }
       }
       return true;
-
       function tryMatch(matchCount) {
         for (let i = 0; i < ms.length; i++) {
           if (seen[i]) continue;
-          expression.mark();
-          if (!ms[i].match(expression)) {
-            expression.popMark(true);
+          expr.mark();
+          if (!ms[i].matchFunc(expr)) {
+            expr.popMark(true);
             continue;
           }
           seen[i] = true;
           // Increase matchCount if this was a required element
           // (or if all the elements are optional)
           if (tryMatch(matchCount + (required === false || required[i] ? 1 : 0))) {
-            expression.popMark(true);
+            expr.popMark(true);
             return true;
           }
           // Backtrack: try *not* matching using this rule, and
           // let's see if it leads to a better overall match.
-          expression.popMark();
+          expr.popMark();
           seen[i] = false;
         }
         if (pass === 0) {
@@ -2029,24 +1748,33 @@ self.parserlib = (() => {
           return matchCount === max;
         }
       }
-    },
-  };
+    }
+    /**
+     * @this {Matcher}
+     * @param {PropertyValueIterator} expr
+     */
+    static funcSeq(expr) {
+      return this.options.every(Matcher.invoke, expr);
+    }
 
-  Matcher.toStringFunc = {
+    /**************************** toStringFunc **********************/
 
-    alt(prec) {
+    /** @this {Matcher} */
+    static toStringAlt(prec) {
       const p = Matcher.prec.ALT;
       const s = this.options.map(m => m.toString(p)).join(' | ');
       return prec > p ? `[ ${s} ]` : s;
-    },
-
-    seq(prec) {
-      const p = Matcher.prec.SEQ;
-      const s = this.options.map(m => m.toString(p)).join(' ');
-      return prec > p ? `[ ${s} ]` : s;
-    },
-
-    many(prec) {
+    }
+    /** @this {Matcher} */
+    static toStringBraces() {
+      const {marker, min, max, embraced} = this.options;
+      return embraced.toString(Matcher.prec.MOD) + (
+        !marker || marker === '#'
+          ? `${marker || ''}{${min}${min === max ? '' : ',' + max}}`
+          : marker);
+    }
+    /** @this {Matcher} */
+    static toStringMany(prec) {
       const {options: ms, required} = this;
       const p = required === false ? Matcher.prec.OROR : Matcher.prec.ANDAND;
       const s = ms.map((m, i) => {
@@ -2057,31 +1785,49 @@ self.parserlib = (() => {
         return m.toString(p);
       }).join(required === false ? ' || ' : ' && ');
       return prec > p ? `[ ${s} ]` : s;
-    },
+    }
+    /** @this {Matcher} */
+    static toStringSeq(prec) {
+      const p = Matcher.prec.SEQ;
+      const s = this.options.map(m => m.toString(p)).join(' ');
+      return prec > p ? `[ ${s} ]` : s;
+    }
+  }
+
+  // Precedence table of combinators.
+  Matcher.prec = {
+    MOD: 5,
+    SEQ: 4,
+    ANDAND: 3,
+    OROR: 2,
+    ALT: 1,
   };
 
   Matcher.parseGrammar = (() => {
+    /** @type {StringReader} */
     let reader;
     return newReader => {
       reader = newReader;
-      return expr();
+      return alt();
     };
-    function expr() {
-      // expr = oror (" | " oror)*
+    function alt() {
+      // alt = oror (" | " oror)*
       const m = [oror()];
       while (reader.readMatch(' | ')) {
         m.push(oror());
       }
       return m.length === 1 ? m[0] : Matcher.alt(...m);
     }
+    // Matcher for two or more options in any order, at least one must be present.
     function oror() {
       // oror = andand ( " || " andand)*
       const m = [andand()];
       while (reader.readMatch(' || ')) {
         m.push(andand());
       }
-      return m.length === 1 ? m[0] : Matcher.oror(...m);
+      return m.length === 1 ? m[0] : Matcher.many(false, ...m);
     }
+    // Matcher for two or more options in any order, all mandatory.
     function andand() {
       // andand = seq ( " && " seq)*
       const m = [seq()];
@@ -2104,152 +1850,163 @@ self.parserlib = (() => {
     }
     function seq() {
       // seq = mod ( " " mod)*
-      const m = [mod()];
+      const ms = [mod()];
       while (reader.readMatch(/\s(?![&|\]])/y)) {
-        m.push(mod());
+        ms.push(mod());
       }
-      return m.length === 1 ? m[0] : Matcher.seq(...m);
+      return Matcher.seq(...ms);
     }
     function mod() {
       // mod = term ( "?" | "*" | "+" | "#" | "{<num>,<num>}" )?
-      const m = term();
+      // term = <nt> | literal | "[ " expression " ]"
+      let m;
+      if (reader.readMatch('[ ')) {
+        m = alt();
+        eat(' ]');
+      } else {
+        m = Matcher.fromType(eat(/[^\s?*+#{]+/y));
+      }
       reader.mark();
       let hash;
       switch (reader.read()) {
-        case '?': return m.question();
-        case '*': return m.star();
-        case '+': return m.plus();
+        case '?': return m.braces(0, 1, '?');
+        case '*': return m.braces(0, Infinity, '*');
+        case '+': return m.braces(1, Infinity, '+');
         case '#':
-          if (reader.peek() !== '{') return m.hash();
+          if (reader.peek() !== '{') return m.braces(1, Infinity, '#', ',');
           reader.read();
           hash = '#';
           // fallthrough
         case '{': {
-          const min = eat(/\s*\d+\s*/y).trim();
-          const c = eat(/[,}]/y);
-          const max = c === ',' ? eat(/\s*\d+\s*}/y).slice(0, -1).trim() : min;
-          return m.braces(Number(min), Number(max), hash, hash && Matcher.cast(','));
+          const [min, max] = eat(/\s*\d+\s*(,\s*\d+\s*)?}/y).trim().split(/\s+|,|}/);
+          return m.braces(min | 0, max | min | 0, hash, hash && ',');
         }
         default:
           reader.reset();
       }
       return m;
     }
-    function term() {
-      // term = <nt> | literal | "[ " expression " ]"
-      if (reader.readMatch('[ ')) {
-        const m = expr();
-        eat(' ]');
-        return m;
-      }
-      return Matcher.fromType(eat(/[^\s?*+#{]+/y));
+    function eat(pattern) {
+      const s = reader.readMatch(pattern);
+      if (s != null) return s;
+      throw new Error('Internal grammar error. ' +
+        `Expected ${pattern} at ${reader._cursor} in ${reader._input}`);
     }
-    function eat(matcher) {
-      const result = reader.readMatch(matcher);
-      if (result == null) {
-        throw new Error(`Internal error. Expected ${matcher} at ${reader._line}:${reader._col}.`);
-      }
-      return result;
-    }
-    function isOptional(item) {
-      return !Array.isArray(item.options) && item.toString().endsWith('?');
+    function isOptional({options}) {
+      return options && options.marker === '?';
     }
   })();
 
-  //endregion
-  //region EventTarget
+  //#endregion
+  //#region EventTarget
 
   class EventTarget {
-
     constructor() {
       this._listeners = new Map();
     }
-
     addListener(type, fn) {
-      let listeners = this._listeners.get(type);
-      if (!listeners) this._listeners.set(type, (listeners = new Set()));
-      listeners.add(fn);
+      let list = this._listeners.get(type);
+      if (!list) this._listeners.set(type, (list = new Set()));
+      list.add(fn);
     }
-
     fire(event) {
       if (typeof event === 'string') {
         event = {type: event};
       }
-      if (typeof event.target !== 'undefined') {
-        event.target = this;
-      }
-
-      if (typeof event.type === 'undefined') {
-        throw new Error("Event object missing 'type' property.");
-      }
-
-      const listeners = this._listeners.get(event.type);
-      if (!listeners) return;
-      for (const fn of listeners.values()) {
-        fn.call(this, event);
+      event.target = this;
+      const list = this._listeners.get(event.type);
+      if (list) {
+        for (const fn of list) {
+          fn.call(this, event);
+        }
       }
     }
-
     removeListener(type, fn) {
-      const listeners = this._listeners.get(type);
-      if (listeners) listeners.delete(fn);
+      const list = this._listeners.get(type);
+      if (list) list.delete(fn);
     }
   }
 
-  //endregion
-  //region SyntaxUnit
+  //#endregion
+  //#region Syntax units
 
+  /** @property {boolean|number} [_isAttr] */
+  /** @property {boolean|number} [_isCalc] */
+  /** @property {boolean|number} [_isVar] */
   class SyntaxUnit {
-
-    constructor(text, pos, type) {
-      this.col = pos.col || pos.startCol;
-      this.line = pos.line || pos.startLine;
+    constructor(text, pos, type, extras) {
+      this.col = pos.col;
+      this.line = pos.line;
       this.offset = pos.offset;
       this.text = text;
       this.type = type;
+      if (extras) Object.assign(this, extras);
     }
-
     valueOf() {
       return this.text;
     }
-
     toString() {
       return this.text;
     }
-
+    get isAttr() {
+      let res = this._isAttr;
+      if (res === 0) res = this._isAttr = lowerCmp(this.name, 'attr');
+      return res;
+    }
+    get isCalc() {
+      let res = this._isCalc;
+      if (res === 0) res = this._isCalc = rxCalc.test(this.text);
+      return res;
+    }
+    get isVar() {
+      let res = this._isVar;
+      if (res === 0) {
+        const pp = this.expr && this.expr.parts;
+        res = this._isVar = pp && pp.length > 0 && (
+          (pp.length === 1 || pp[1].text === ',') && (
+            pp[0].type === 'custom-property' && lowerCmp(this.name, 'var') ||
+            pp[0].type === 'identifier' && lowerCmp(this.name, 'env')));
+      }
+      return res;
+    }
     static fromToken(token) {
-      return new SyntaxUnit(token.value, token);
+      return token && new SyntaxUnit(token.value, token);
+    }
+
+    /**
+     * @param {SyntaxUnit} unit
+     * @param {SyntaxUnit|parserlib.Token} token
+     * @returns {SyntaxUnit}
+     */
+    static addFuncInfo(unit, {expr, name} = unit) {
+      const isColor = expr && expr.parts && /^(rgb|hsl)a?$/i.test(name);
+      if (isColor) unit.type = 'color';
+      unit._isAttr =
+        unit._isCalc =
+          unit._isVar = isColor ? false : 0;
+      return unit;
     }
   }
 
-  //endregion
-  //region SyntaxError
-
   class SyntaxError extends Error {
     constructor(message, pos) {
       super();
       this.name = this.constructor.name;
-      this.col = pos.col || pos.startCol;
-      this.line = pos.line || pos.startLine;
+      this.col = pos.col;
+      this.line = pos.line;
       this.message = message;
     }
   }
 
-  //endregion
-  //region ValidationError
-
   class ValidationError extends Error {
     constructor(message, pos) {
       super();
-      this.col = pos.col || pos.startCol;
-      this.line = pos.line || pos.startLine;
+      this.col = pos.col;
+      this.line = pos.line;
       this.message = message;
     }
   }
 
-  //endregion
-  //region MediaQuery
-
   // individual media query
   class MediaQuery extends SyntaxUnit {
     /**
@@ -2269,23 +2026,16 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region MediaFeature
-
   // e.g. max-width:500.
   class MediaFeature extends SyntaxUnit {
     constructor(name, value) {
       const text = `(${name}${value != null ? ':' + value : ''})`;
       super(text, name, TYPES.MEDIA_FEATURE_TYPE);
-
       this.name = name;
       this.value = value;
     }
   }
 
-  //endregion
-  //region Selector
-
   /**
    * An entire single selector, including all parts but not
    * including multiple selectors (those separated by commas).
@@ -2302,9 +2052,6 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region SelectorPart
-
   /**
    * A single part of a selector string i.e. element name and modifiers.
    * Does not include combinators such as spaces, +, >, etc.
@@ -2321,9 +2068,6 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region SelectorSubPart
-
   /**
    * Selector modifier string
    */
@@ -2339,14 +2083,10 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region Combinator
-
   /**
    * A selector combinator (whitespace, +, >).
    */
   class Combinator extends SyntaxUnit {
-
     constructor(token) {
       const {value} = token;
       super(value, token, TYPES.COMBINATOR_TYPE);
@@ -2360,9 +2100,6 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region Specificity
-
   /**
    * A selector specificity.
    */
@@ -2380,7 +2117,6 @@ self.parserlib = (() => {
       this.d = d;
       this.constructor = Specificity;
     }
-
     /**
      * @param {Specificity} other The other specificity to compare to.
      * @return {int} -1 if the other specificity is larger, 1 if smaller, 0 if equal.
@@ -2396,21 +2132,18 @@ self.parserlib = (() => {
       }
       return 0;
     }
-
     /**
      * @return {int} The numeric value for the specificity.
      */
     valueOf() {
       return (this.a * 1000) + (this.b * 100) + (this.c * 10) + this.d;
     }
-
     /**
      * @return {String} The string representation of specificity.
      */
     toString() {
       return this.a + ',' + this.b + ',' + this.c + ',' + this.d;
     }
-
     /**
      * Calculates the specificity of the given selector.
      * @param {Selector} The selector to calculate specificity for.
@@ -2422,7 +2155,6 @@ self.parserlib = (() => {
       let d = 0;
       selector.parts.forEach(updateValues);
       return new Specificity(0, b, c, d);
-
       function updateValues(part) {
         if (!(part instanceof SelectorPart)) return;
         const elementName = part.elementName ? part.elementName.text : '';
@@ -2435,11 +2167,9 @@ self.parserlib = (() => {
             case 'attribute':
               c++;
               break;
-
             case 'id':
               b++;
               break;
-
             case 'pseudo':
               if (isPseudoElement(modifier.text)) {
                 d++;
@@ -2447,7 +2177,6 @@ self.parserlib = (() => {
                 c++;
               }
               break;
-
             case 'not':
               modifier.args.forEach(updateValues);
           }
@@ -2456,25 +2185,17 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region PropertyName
-
   class PropertyName extends SyntaxUnit {
-
     constructor(text, hack, pos) {
       super(text, pos, TYPES.PROPERTY_NAME_TYPE);
       // type of IE hack applied ("*", "_", or null).
       this.hack = hack;
     }
-
     toString() {
       return (this.hack || '') + this.text;
     }
   }
 
-  //endregion
-  //region PropertyValue
-
   /**
    * A single value between ":" and ";", that is if there are multiple values
    * separated by commas, this type represents just one of the values.
@@ -2489,124 +2210,16 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region PropertyValuePart
-
-  const tokenConverter = new Map([
-    ...(fn => [
-      Tokens.LENGTH,
-      Tokens.ANGLE,
-      Tokens.TIME,
-      Tokens.FREQ,
-      Tokens.DIMENSION,
-      Tokens.PERCENTAGE,
-      Tokens.NUMBER,
-    ].map(tt => [tt, fn]))((self, {number, units, unitsType}) => {
-      self.value = number;
-      self.units = units;
-      self.type = unitsType === 'number' && !self.text.includes('.') ? 'integer' : unitsType;
-    }),
-
-    [Tokens.HASH, (self, {value}) => {
-
-      self.type = 'color';
-      if (value.length <= 5) {
-        let n = parseInt(value.slice(1), 16);
-        if (value.length === 5) {
-          self.alpha = (n & 15) << 4 + (n & 15);
-          n >>= 4;
-        }
-        self.red = (n >> 8 & 15) << 4 + (n >> 8 & 15);
-        self.green = (n >> 4 & 15) << 4 + (n >> 4 & 15);
-        self.blue = (n & 15) << 4 + (n & 15);
-      } else {
-        const n = parseInt(value.substr(1, 6), 16);
-        self.red = n >> 16;
-        self.green = (n >> 8) & 255;
-        self.blue = n & 255;
-        if (value.length === 9) {
-          self.alpha = parseInt(value.substr(7, 2), 16);
-        }
-      }
-
-    }],
-    [Tokens.FUNCTION, (self, {name, expr}) => {
-
-      self.name = name;
-      self.expr = expr;
-      const parts = expr && expr.parts;
-      switch (parts && lower(name)) {
-        case 'rgb':
-        case 'rgba': {
-          const [r, g, b, a] = parts.map(p => !/[,/]/.test(p)).map(parseFloat);
-          const pct = parts[0].tokenType === Tokens.PERCENTAGE ? 2.55 : 1;
-          self.type = 'color';
-          self.red = r * pct;
-          self.green = g * pct;
-          self.blue = b * pct;
-          if (!isNaN(a)) self.alpha = a * (/%/.test(parts[parts.length - 1]) ? 2.55 / 100 : 1);
-          return;
-        }
-        case 'hsl':
-        case 'hsla': {
-          const [h, s, l, a] = parts.map(p => !/[,/]/.test(p)).map(parseFloat);
-          self.type = 'color';
-          self.hue = h;
-          self.hueUnit = parts[0].units;
-          self.saturation = s;
-          self.lightness = l;
-          if (!isNaN(a)) self.alpha = a * (/%/.test(parts[parts.length - 1]) ? 2.55 / 100 : 1);
-          return;
-        }
-        default:
-          self.type = 'function';
-      }
-
-    }],
-    [Tokens.URI, (self, {name, uri}) => {
-
-      self.type = 'uri';
-      self.name = name;
-      self.uri = uri;
-
-    }],
-    [Tokens.STRING, self => {
-
-      self.type = 'string';
-      self.value = parseString(self.text);
-
-    }],
-    [Tokens.IDENT, self => {
-
-      const text = self.text;
-      let namedColor;
-      if (!text.includes('-') && (namedColor = Colors[text] || Colors[lower(text)])) {
-        tokenConverter.get(Tokens.HASH)(self, {value: namedColor});
-      } else {
-        self.type = 'identifier';
-        self.value = text;
-      }
-
-    }],
-    [Tokens.CUSTOM_PROP, self => {
-
-      self.type = 'custom-property';
-      self.value = self.text;
-
-    }],
-  ]);
-
   /**
    * A single part of a value
    * e.g. '1px solid rgb(1, 2, 3)' has 3 parts
+   * @property {PropertyValue} expr
    */
   class PropertyValuePart extends SyntaxUnit {
-
+    /** @type {parserlib.Token} */
     constructor(token) {
       const {value, type} = token;
       super(value, token, TYPES.PROPERTY_VALUE_PART_TYPE);
-
-      this.type = 'unknown';
       this.tokenType = type;
       if (token.expr) this.expr = token.expr;
       // There can be ambiguity with escape sequences in identifiers, as
@@ -2614,21 +2227,66 @@ self.parserlib = (() => {
       // an explicit hint when the token generating this PropertyValuePart
       // was an identifier.
       this.wasIdent = type === Tokens.IDENT;
-
-      const cvt = tokenConverter.get(type);
-      if (cvt && cvt(this, token) !== false) return;
-
-      if (value === ',' || value === '/') {
-        this.type = 'operator';
-        this.value = value;
-        return;
+      switch (type) {
+        case Tokens.ANGLE:
+        case Tokens.DIMENSION:
+        case Tokens.FREQ:
+        case Tokens.LENGTH:
+        case Tokens.NUMBER:
+        case Tokens.PERCENTAGE:
+        case Tokens.TIME:
+          this.value = token.number;
+          this.units = token.units;
+          this.type = token.unitsType;
+          this.isInt = this.type === 'number' && !value.includes('.');
+          break;
+        case Tokens.CUSTOM_PROP:
+          this.type = 'custom-property';
+          this.value = this.text;
+          break;
+        case Tokens.HASH:
+          this.type = 'color';
+          this.value = value;
+          break;
+        case Tokens.IDENT: {
+          const namedColor = !value.includes('-') && (Colors[value] || Colors[lower(value)]);
+          if (namedColor) {
+            this.type = 'color';
+            this.value = namedColor;
+          } else {
+            this.type = 'identifier';
+            this.value = value;
+          }
+          break;
+        }
+        case Tokens.FUNCTION: {
+          this.name = token.name;
+          SyntaxUnit.addFuncInfo(this, token);
+          break;
+        }
+        case Tokens.STRING:
+          this.type = 'string';
+          this.value = parseString(value);
+          break;
+        case Tokens.URI:
+          this.type = 'uri';
+          this.name = token.name;
+          this.uri = token.uri;
+          break;
+        case Tokens.USO_VAR:
+          this._isVar = true;
+          break;
+        default:
+          if (value === ',' || value === '/') {
+            this.type = 'operator';
+            this.value = value;
+          } else {
+            this.type = 'unknown';
+          }
       }
     }
   }
 
-  //endregion
-  //region PropertyValueIterator
-
   // A utility class that allows for easy iteration over the various parts of a property value.
   class PropertyValueIterator {
     /**
@@ -2639,168 +2297,180 @@ self.parserlib = (() => {
       this._parts = value.parts;
       this._marks = [];
       this.value = value;
+      this.hasNext = this._parts.length > 0;
     }
-
-    hasNext() {
-      return this._i < this._parts.length;
-    }
-
+    /** @returns {PropertyValuePart|null} */
     peek(count) {
       return this._parts[this._i + (count || 0)] || null;
     }
-
+    /** @returns {?PropertyValuePart} */
     next() {
-      return this._i < this._parts.length ? this._parts[this._i++] : null;
+      if (this.hasNext) {
+        this.hasNext = this._i + 1 < this._parts.length;
+        return this._parts[this._i++];
+      }
     }
+    /** @returns {PropertyValueIterator} */
     mark() {
       this._marks.push(this._i);
       return this;
     }
-
     popMark(success) {
       const i = this._marks.pop();
       if (!success && i != null) {
         this._i = i;
+        this.hasNext = i < this._parts.length;
       }
       return success;
     }
+    resetTo(i) {
+      this._i = i;
+      this.hasNext = this._parts.length > i;
+    }
   }
 
-  //endregion
-  //region ValidationTypes - methods
+  //#endregion
+  //#region ValidationTypes - implementation
 
-  Object.assign(ValidationTypes, {
-
-    /**
-     * @param {string} name
-     * @param {PropertyValuePart} part
-     * @returns {boolean}
-     * @throws {ValidationError}
-     */
-    isFunction(name, {expr}) {
-      // no parameter means the initial value is used so it's a valid function call
-      if (!expr) {
-        return this.functionsMayBeEmpty.has(name);
-      }
-      // USO vars can span any number of grammar parts so not gonna try to guess. KISS.
-      if (expr.parts.some(p => p.tokenType === Tokens.USO_VAR)) {
-        return true;
-      }
-      const fn = this.functions[name];
-      if (!fn) {
-        return true;
-      }
-      const vi = new PropertyValueIterator(expr);
-      if (fn.match(vi) && !vi.hasNext()) {
-        return true;
-      }
-      throw new ValidationError(
-        `Expected '${this.explode(`${fn}`)}' but found '${vi.value.text}'.`, vi.value);
-    },
-
-    /**
-     * @param {string} literals
-     * @param {PropertyValuePart} part
-     * @return {?boolean}
-     */
-    isLiteral(literals, part) {
-      let text;
-      for (const arg of literals.includes(' | ') ? literals.split(' | ') : [literals]) {
-        if (arg.startsWith('<')) {
-          if (arg in this.simple && this.simple[arg](part)) {
-            return true;
-          }
-        } else if (
-          arg.endsWith('()') &&
-          part.type === 'function' &&
-          part.name && part.name.length === arg.length - 2
-        ) {
-          const name = arg.slice(0, -2);
-          const isFn = lowerCmp(name, part.name) ? this.isFunction(name, part) : null;
-          if (isFn != null) {
-            return isFn;
-          }
-        } else if (part.text.length >= arg.length) {
-          if (!text) text = RX_VENDOR_PREFIX.test(text) ? RegExp.$2 : part.text;
-          if (lowerCmp(text, arg)) {
-            return true;
-          }
-        }
-      }
-    },
-
-    /**
-     * @param {PropertyValueIterator} expr
-     * @param {string} type
-     * @return {?boolean}
-     */
-    isType(expr, type) {
-      const part = expr.peek();
-      let result, m;
-
-      if (this.simple['<var>'](part)) {
-        if (expr._i < expr._parts.length - 1) {
-          expr.mark().next();
-          expr.popMark(ValidationTypes.isType(expr, type));
-        }
-        result = true;
-
-      } else if (!type.startsWith('<')) {
-        result = this.isLiteral(type, part);
-
-      } else if ((m = this.simple[type])) {
-        result = m.call(this.simple, part);
-
-      } else {
-        m = this.complex[type];
-        return m instanceof Matcher ?
-          m.match(expr) :
-          m.call(this.complex, expr);
-      }
-
-      if (!result && expr.tryAttr && part.type === 'function' && lowerCmp(part.name, 'attr')) {
-        result = ValidationTypes.isFunction('attr', part);
-      }
-      if (result) expr.next();
-      return result;
-    },
-
-    describe(type) {
-      const complex = this.complex[type];
-      const text = complex instanceof Matcher ? complex.toString(0) : type;
-      return this.explode(text);
-    },
-
-    explode(text) {
-      if (!text.includes('<')) return text;
-      return text
-        .replace(' | <var>', '')
-        .replace(/(<.*?>)([{#?]?)/g,
-          (_, rule, mod) => {
-            const ref = this.simple[rule] || this.complex[rule];
-            if (!ref || !ref.originalText) return rule + mod;
-            return ((mod ? '[' : '') + this.explode(ref.originalText) + (mod ? ']' : '')) + mod;
-          });
-    },
-  });
-
-  for (const name of ['simple', 'complex', 'functions']) {
-    const action = name === 'simple'
-      ? rule => ValidationTypes.isLiteral.bind(ValidationTypes, rule)
+  for (const obj of [VTSimple, VTComplex, VTFunctions]) {
+    const action = obj === VTSimple
+      ? rule => vtIsLiteral.bind(obj, rule)
       : Matcher.parse;
-    const set = ValidationTypes[name];
-    for (const id in set) {
-      const rule = set[id];
+    for (const [id, rule] of Object.entries(obj)) {
       if (typeof rule === 'string') {
-        set[id] = Object.defineProperty(action(rule), 'originalText', {value: rule});
+        obj[id] = Object.defineProperty(action(rule), 'originalText', {value: rule});
       } else if (/^Matcher\s/.test(rule)) {
-        set[id] = rule(Matcher);
+        obj[id] = rule(Matcher);
       }
     }
   }
 
-  //endregion
-  //region Validation
+  /**
+   * @param {string} name
+   * @param {PropertyValue} expr
+   */
+  function vtFunc(name, {expr}) {
+    // no parameter means the initial value is used so it's a valid function call
+    if (!expr) {
+      return VTFunctionsMayBeEmpty.has(name);
+    }
+    // USO vars can span any number of grammar parts so not gonna try to guess. KISS.
+    if (expr.parts.some(hasUsoVarPart)) {
+      return true;
+    }
+    /** @type {Matcher} */
+    const fn = VTFunctions[name];
+    if (!fn) {
+      return true;
+    }
+    const vi = new PropertyValueIterator(expr);
+    if (fn.match(vi) && !vi.hasNext) {
+      return true;
+    }
+    throw new ValidationError(`Expected '${vtExplode(`${fn}`)}' but found '${vi.value.text}'.`,
+      vi.value);
+  }
+
+  function vtDescribe(type) {
+    const complex = VTComplex[type];
+    const text = complex instanceof Matcher ? complex.toString(0) : type;
+    return vtExplode(text);
+  }
+
+  function vtExplode(text) {
+    if (!text.includes('<')) return text;
+    return text.replace(/(<.*?>)([{#?]?)/g, (_, rule, mod) => {
+      const ref = VTSimple[rule] || VTComplex[rule];
+      if (!ref || !ref.originalText) return rule + mod;
+      const full = vtExplode(ref.originalText);
+      const brace = mod || full.includes(' ');
+      return ((brace ? '[ ' : '') + full + (brace ? ' ]' : '')) + mod;
+    });
+  }
+
+  /** @param {PropertyValuePart} p */
+  function vtIsIdent(p) {
+    return p.type === 'identifier' || p.wasIdent;
+  }
+
+  /** @param {PropertyValuePart} p */
+  function vtIsLength(p) {
+    return p.text === '0' || p.type === 'length' || p.type === 'number' || p.isCalc;
+  }
+
+  /**
+   * @param {string} literals
+   * @param {PropertyValuePart} part
+   * @return {?boolean}
+   */
+  function vtIsLiteral(literals, part) {
+    let text;
+    for (const arg of literals.includes(' | ') ? literals.split(' | ') : [literals]) {
+      if (arg.startsWith('<')) {
+        const vt = VTSimple[arg];
+        if (vt && vt(part)) {
+          return true;
+        }
+        continue;
+      }
+      if (arg.endsWith('()') &&
+          part.tokenType === Tokens.FUNCTION &&
+          part.name.length === arg.length - 2) {
+        const fnName = arg.slice(0, -2);
+        const isFn = arg.startsWith(part.name) || lowerCmp(fnName, part.name)
+          ? vtFunc(fnName, part)
+          : null;
+        if (isFn != null) {
+          return isFn;
+        }
+        continue;
+      }
+      if ((text || part.text) === arg ||
+          (text || part.text).length >= arg.length &&
+          lowerCmp(arg, text || (text = rxVendorPrefix.test(part.text) ? RegExp.$2 : part.text))) {
+        return true;
+      }
+    }
+  }
+
+  /** @param {PropertyValuePart} p */
+  function vtIsPct(p) {
+    return p.text === '0' || p.type === 'percentage' || p.isCalc;
+  }
+
+  /**
+   * @param {PropertyValueIterator} expr
+   * @param {string} type
+   * @return {?boolean}
+   */
+  function vtIsType(expr, type) {
+    const part = expr.peek();
+    let result, m;
+    if (part.isVar) {
+      if (expr._i < expr._parts.length - 1) {
+        expr.mark().next();
+        expr.popMark(vtIsType(expr, type));
+      }
+      result = true;
+    } else if (!type.startsWith('<')) {
+      result = vtIsLiteral(type, part);
+    } else if ((m = VTSimple[type])) {
+      result = m.call(VTSimple, part);
+    } else {
+      m = VTComplex[type];
+      return m instanceof Matcher ?
+        m.match(expr) :
+        m.call(VTComplex, expr);
+    }
+    if (!result && expr.tryAttr && part.isAttr) {
+      result = vtFunc('attr', part);
+    }
+    if (result) expr.next();
+    return result;
+  }
+
+  //#endregion
+  //#region Validation
 
   const validationCache = new Map();
 
@@ -2813,64 +2483,59 @@ self.parserlib = (() => {
       }
       return;
     }
-
     const prop = lower(property);
     let known = validationCache.get(prop);
-    if (known && known.has(value.text)) return;
-
-    const spec = Properties[prop] || RX_VENDOR_PREFIX.test(prop) && Properties[RegExp.$2];
-
-    if (typeof spec === 'number') return;
-    if (!spec && prop.startsWith('-')) return;
-    if (!spec) throw new ValidationError(`Unknown property '${property}'.`, property);
-
+    if (known && known.has(value.text)) {
+      return;
+    }
+    const spec = Properties[prop] || rxVendorPrefix.test(prop) && Properties[RegExp.$2];
+    if (typeof spec === 'number' || !spec && prop.startsWith('-')) {
+      return;
+    }
+    if (!spec) {
+      throw new ValidationError(`Unknown property '${property}'.`, property);
+    }
     // Property-specific validation.
     const expr = new PropertyValueIterator(value);
-    const tryAttr = /\battr\(/i.test(value.text);
     const m = Matcher.parse(spec);
     let result = m.match(expr);
-    if (tryAttr) {
+    if (/\battr\(/i.test(value.text)) {
       if (!result) {
         expr.tryAttr = true;
-        expr._i = 0;
+        expr.resetTo(0);
         result = m.match(expr);
       }
-      while (expr.hasNext() &&
-          ValidationTypes.simple['<attr>'](expr.peek()) &&
-          ValidationTypes.isFunction('attr', expr.peek())) {
+      for (let p; (p = expr.peek()) && p.isAttr && vtFunc('attr', p);) {
         expr.next();
       }
     }
     if (result) {
-      if (expr.hasNext()) throwEndExpected(expr.next());
-    } else if (expr.hasNext() && expr._i) {
+      if (expr.hasNext) throwEndExpected(expr.next());
+    } else if (expr.hasNext && expr._i) {
       throwEndExpected(expr.peek());
     } else {
       const {text} = expr.value;
-      throw new ValidationError(`Expected '${ValidationTypes.describe(spec)}' but found '${text}'.`,
+      throw new ValidationError(`Expected '${vtDescribe(spec)}' but found '${text}'.`,
         expr.value);
     }
-
     if (!known) validationCache.set(prop, (known = new Set()));
     known.add(value.text);
-
-    function throwEndExpected(token, force) {
-      if (force || (token.name !== 'var' && token.name !== 'env') || token.type !== 'function') {
-        throw new ValidationError(`Expected end of value but found '${token.text}'.`, token);
+    function throwEndExpected(unit, force) {
+      if (force || !unit.isVar) {
+        throw new ValidationError(`Expected end of value but found '${unit.text}'.`, unit);
       }
     }
   }
 
-  //endregion
-  //region TokenStreamBase
+  //#endregion
+  //#region TokenStreamBase
 
-  /**
-   * lookup table size for TokenStreamBase
-   */
+  /** lookup table size for TokenStreamBase */
   const LT_SIZE = 5;
 
   /**
    * Generic TokenStream providing base functionality.
+   * @typedef TokenStream
    */
   class TokenStreamBase {
 
@@ -2880,24 +2545,27 @@ self.parserlib = (() => {
     }
 
     resetLT() {
-      // Token object for the last consumed token.
+      /** @type {parserlib.Token} Last consumed token object */
       this._token = null;
       // Lookahead token buffer.
-      this._lt = [];
+      this._lt = Array(LT_SIZE).fill(null);
       this._ltIndex = 0;
-      this._ltIndexCache = [];
+      this._ltAhead = 0;
+      this._ltShift = 0;
     }
 
     /**
      * Consumes the next token if that matches any of the given token type(s).
      * @param {int|int[]} tokenTypes
-     * @return {Object|false}
+     * @param {string|string[]} [values]
+     * @return {parserlib.Token|boolean} token or `false`
      */
-    match(tokenTypes) {
+    match(tokenTypes, values) {
       const isArray = typeof tokenTypes === 'object';
-      for (let tt; (tt = this.get());) {
-        if (isArray ? tokenTypes.includes(tt) : tt === tokenTypes) {
-          return this._token;
+      for (let token, tt; (tt = (token = this.get(true)).type);) {
+        if ((isArray ? tokenTypes.includes(tt) : tt === tokenTypes) &&
+            (!values || values.some(lowerCmpThis, token.value))) {
+          return token;
         }
         if (tt !== Tokens.COMMENT) {
           break;
@@ -2914,12 +2582,8 @@ self.parserlib = (() => {
      * @throws {SyntaxError}
      */
     mustMatch(tokenTypes) {
-      if (!this.match(tokenTypes)) {
-        const {startLine: line, startCol: col, offset} = this.LT(1);
-        const info = Tokens[Array.isArray(tokenTypes) ? tokenTypes[0] : tokenTypes];
-        throw new SyntaxError(`Expected ${info.text || info.name} at line ${line}, col ${col}.`, {line, col, offset});
-      }
-      return this._token;
+      return this.match(tokenTypes) ||
+        this.throwUnexpected(this.LT(1), tokenTypes);
     }
 
     /**
@@ -2935,47 +2599,34 @@ self.parserlib = (() => {
 
     /**
      * Consumes the next token from the token stream.
-     * @return {int} The token type
+     * @param {boolean} [asToken]
+     * @return {int|parserlib.Token} The token type
      */
-    get() {
-      const cache = this._ltIndexCache;
-      const lt = this._lt;
-      let i = 0;
-
-      // check the lookahead buffer first
-      let len = lt.length;
-      let ltIndex = this._ltIndex;
-      if (len && ltIndex >= 0 && ltIndex < len) {
-        i++;
-        this._token = lt[ltIndex];
-        this._ltIndex = ++ltIndex;
-        if (ltIndex <= len) {
-          cache.push(i);
-          return this._token.type;
+    get(asToken) {
+      const i = this._ltIndex;
+      const next = i + 1;
+      const slot = (i + this._ltShift) % LT_SIZE;
+      if (i < this._ltAhead) {
+        this._ltIndex = next;
+        const token = this._token = this._lt[slot];
+        return asToken ? token : token.type;
+      }
+      const token = this._getToken();
+      const {type} = token;
+      const hide = type && (Tokens[type] || {}).hide;
+      if (type >= 0 && !hide) {
+        this._token = token;
+        this._lt[slot] = token;
+        if (this._ltAhead < LT_SIZE) {
+          this._ltIndex = next;
+          this._ltAhead++;
+        } else {
+          this._ltShift = (this._ltShift + 1) % LT_SIZE;
         }
       }
-
-      const token = this._getToken();
-      const type = token.type;
-      const isHidden = Tokens[type].hide;
-
-      if (type > -1 && !isHidden) {
-        // save for later
-        this._token = token;
-        lt.push(token);
-
-        // save space that will be moved (must be done before array is truncated)
-        cache.push(++len - ltIndex + i);
-
-        if (len > LT_SIZE) lt.shift();
-        if (cache.length > LT_SIZE) cache.shift();
-
-        // update lookahead index
-        this._ltIndex = lt.length;
-      }
-
       // Skip to the next token if the token type is marked as hidden.
-      return isHidden ? this.get() : type;
+      return hide ? this.get(asToken) :
+        asToken ? token : type;
     }
 
     /**
@@ -2987,58 +2638,71 @@ self.parserlib = (() => {
      *         or back past the first token in the lookahead buffer.
      */
     LA(index) {
-      if (!index) return this._token.type;
-
-      if (index > 0) {
-        if (index > LT_SIZE) throw new Error('Too much lookahead.');
-        let total = index;
-        let tt;
-        while (total && total--) tt = this.get();
-        while (total++ < index) this.unget();
-        return tt;
-      }
-
-      if (index < 0) {
-        const token = this._lt[this._ltIndex + index];
-        if (!token) throw new Error('Too much lookbehind.');
-        return token.type;
-      }
+      return (index ? this.LT(index) : this._token).type;
     }
 
     /**
      * Looks ahead a certain number of tokens and returns the token at that position.
      * @param {int} index The index of the token type to retrieve.
      *         0 for the current token, 1 for the next, -1 for the previous, etc.
+     * @param {boolean} [forceCache] won't call get() so it's useful in fast tentative checks
      * @return {Object} The token
      * @throws if you lookahead past EOF, past the size of the lookahead buffer,
      *         or back past the first token in the lookahead buffer.
      */
-    LT(index) {
-      // lookahead first to prime the token buffer
-      this.LA(index);
-      // now find the token, subtract one because _ltIndex is already at the next index
-      return this._lt[this._ltIndex + index - 1];
+    LT(index, forceCache) {
+      if (!index) {
+        return this._token;
+      }
+      let i = index + this._ltIndex - (index > 0);
+      if (index < 0 ? i >= 0 : i < this._ltAhead) {
+        return this._lt[(i + this._ltShift) % LT_SIZE];
+      } else if (forceCache) {
+        return false;
+      }
+      if (index < 0) {
+        throw new Error('Too much lookbehind.');
+      }
+      if (index > LT_SIZE) {
+        throw new Error('Too much lookahead.');
+      }
+      i = index;
+      const oldToken = this._token;
+      while (i && i--) this.get();
+      const token = this._token;
+      this._ltIndex -= index;
+      this._token = oldToken;
+      return token;
     }
 
-    // Returns the token type for the next token in the stream without consuming it.
+    /** Returns the token type for the next token in the stream without consuming it. */
     peek() {
-      return this.LA(1);
+      return this.LT(1).type;
     }
 
-    // Restores the last consumed token to the token stream.
+    /** Restores the last consumed token to the token stream. */
     unget() {
-      const cache = this._ltIndexCache;
-      if (cache.length) {
-        this._ltIndex -= cache.pop();
-        this._token = this._lt[this._ltIndex - 1];
+      if (this._ltIndex) {
+        this._ltIndex--;
+        this._token = this._lt[(this._ltIndex - 1 + this._ltShift + LT_SIZE) % LT_SIZE];
       } else {
         throw new Error('Too much lookahead.');
       }
     }
+
+    throwUnexpected(token = this._token, expected = []) {
+      expected = (Array.isArray(expected) ? expected : [expected])
+        .map(e => typeof e === 'string' ? e : Tokens.name(e))
+        .join(', ');
+      const msg = expected
+        ? `Expected ${expected} but found '${token.value}'.`
+        : `Unexpected '${token.value}'.`;
+      throw new SyntaxError(msg, token);
+    }
   }
 
-  //endregion
-  //region TokenStream
+  //#endregion
+  //#region TokenStream
 
   class TokenStream extends TokenStreamBase {
 
@@ -3058,10 +2722,13 @@ self.parserlib = (() => {
      * @param {Boolean} [skipWS] - skip whitespace too
      */
     skipComment(skipWS) {
-      const tt = (this._lt[this._ltIndex] || this.LT(1)).type;
-      if (tt === Tokens.USO_VAR ||
+      const tt = this.LT(1, true).type;
+      if (skipWS && tt === Tokens.S ||
+          tt === Tokens.USO_VAR ||
           tt === Tokens.COMMENT ||
-          skipWS && tt === Tokens.S) {
+          tt == null && this._ltIndex === this._ltAhead && (
+            skipWS && this.readWhitespace(),
+            this._reader.peekTest(/\/\*/y))) {
         while (this.match(TT.usoS)) { /*NOP*/ }
       }
     }
@@ -3078,39 +2745,16 @@ self.parserlib = (() => {
       };
       const c = reader.read();
       switch (c) {
-
-        /*
-         * Potential tokens:
-         * - S
-         */
         case ' ':
         case '\n':
         case '\r':
         case '\t':
         case '\f':
           return this.whitespaceToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - COMMENT
-         * - SLASH
-         * - CHAR
-         */
         case '/':
           return reader.peek() === '*' ?
             this.commentToken(c, pos) :
             this.charToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - DASHMATCH
-         * - INCLUDES
-         * - PREFIXMATCH
-         * - SUFFIXMATCH
-         * - SUBSTRINGMATCH
-         * - COLUMN
-         * - CHAR
-         */
         case '|':
         case '~':
         case '^':
@@ -3123,45 +2767,17 @@ self.parserlib = (() => {
               this.createToken(Tokens.COLUMN, '||', pos) :
               this.charToken(c, pos)
           );
-        /*
-         * Potential tokens:
-         * - STRING
-         * - INVALID
-         */
         case '"':
         case "'":
           return this.stringToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - HASH
-         * - CHAR
-         */
         case '#':
-          return isNameChar(reader.peek()) ?
+          return reader.peekTest(rxNameChar) ?
             this.hashToken(c, pos) :
             this.charToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - DOT
-         * - NUMBER
-         * - DIMENSION
-         * - PERCENTAGE
-         */
         case '.':
-          return isDigit(reader.peek()) ?
+          return reader.peekTest(/\d/y) ?
             this.numberToken(c, pos) :
             this.charToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - CDC
-         * - MINUS
-         * - NUMBER
-         * - DIMENSION
-         * - PERCENTAGE
-         */
         case '-': {
           const next = reader.peek();
           // could be closing HTML-style comment or CSS variable
@@ -3170,83 +2786,34 @@ self.parserlib = (() => {
               /\w/.test(reader.peek(2)) ?
                 this.identOrFunctionToken(c, pos) :
                 this.htmlCommentEndToken(c, pos) :
-            next === '.' && isDigit(reader.peek(2)) ||
-            isDigit(next) ?
+            reader.peekTest(/\.?\d/y) ?
               this.numberToken(c, pos) :
-            isNameStart(next) ?
+            reader.peekTest(rxIdentStart) ? // we can reuse rx for IDENT because '-' is handled above
               this.identOrFunctionToken(c, pos) :
               this.charToken(c, pos)
           );
         }
-        /*
-         * Potential tokens:
-         * - PLUS
-         * - NUMBER
-         * - DIMENSION
-         * - PERCENTAGE
-         */
-        case '+': {
-          const next = reader.peek();
+        case '+':
           return (
-            next === '.' && isDigit(reader.peek(2)) ||
-            isDigit(next) ?
+            reader.peekTest(/\.?\d/y) ?
               this.numberToken(c, pos) :
               this.charToken(c, pos)
           );
-        }
-        /*
-         * Potential tokens:
-         * - IMPORTANT_SYM
-         * - CHAR
-         */
         case '!':
           return this.importantToken(c, pos);
-
-        /*
-         * Any at-keyword or CHAR
-         */
         case '@':
           return this.atRuleToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - ANY
-         * - IS
-         * - NOT
-         * - WHERE
-         * - CHAR
-         */
         case ':':
           return this.notOrIsToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - CDO
-         * - CHAR
-         */
         case '<':
           return this.htmlCommentStartToken(c, pos);
-
-        /*
-         * Potential tokens:
-         * - IDENT
-         * - CHAR
-         */
         case '\\':
-          return /[^\r\n\f]/.test(reader.peek()) ?
+          return reader.peekTest(/[^\r\n\f]/y) ?
             this.identOrFunctionToken(this.readEscape(c), pos) :
             this.charToken(c, pos);
-
         // EOF
         case null:
           return this.createToken(Tokens.EOF, null, pos);
-
-        /*
-         * Potential tokens:
-         * - UNICODE_RANGE
-         * - URL
-         * - CHAR
-         */
         case 'U':
         case 'u':
           if (reader.peek() === '+') {
@@ -3254,31 +2821,13 @@ self.parserlib = (() => {
           }
           // fallthrough
       }
-
-      /*
-       * Potential tokens:
-       * - NUMBER
-       * - DIMENSION
-       * - LENGTH
-       * - FREQ
-       * - TIME
-       * - EMS
-       * - EXS
-       * - ANGLE
-       */
-      if (isDigit(c)) {
-        return this.numberToken(c, pos);
-      }
-
-      /*
-       * Potential tokens:
-       * - IDENT
-       * - CHAR
-       * - PLUS
-       */
-      return isIdentStart(c) ?
-        this.identOrFunctionToken(c, pos) :
-        this.charToken(c, pos);
+      return (
+        c >= '0' && c <= '9' ?
+          this.numberToken(c, pos) :
+        stickyTest(rxIdentStart, 0, c) ?
+          this.identOrFunctionToken(c, pos) :
+          this.charToken(c, pos)
+      );
     }
 
     /**
@@ -3287,11 +2836,11 @@ self.parserlib = (() => {
      * private methods to create tokens and is never called directly.
      */
     createToken(type, value, pos, opts) {
-      const token = {
+      const token = /** @namespace parserlib.Token */{
         value,
         type,
-        startLine: pos.line,
-        startCol: pos.col,
+        line: pos.line,
+        col: pos.col,
         offset: pos.offset,
       };
       if (opts && opts.endChar) token.endChar = opts.endChar;
@@ -3404,7 +2953,7 @@ self.parserlib = (() => {
       return this.createToken(type, name, pos);
     }
 
-    // IMPORTANT_SYM
+    // IMPORTANT
     // CHAR
     importantToken(first, pos) {
       const reader = this._reader;
@@ -3413,7 +2962,7 @@ self.parserlib = (() => {
       for (let pass = 1; pass++ <= 2;) {
         const important = reader.readMatch(/\s*important\b/iy);
         if (important) {
-          return this.createToken(Tokens.IMPORTANT_SYM, text + important, pos);
+          return this.createToken(Tokens.IMPORTANT, text + important, pos);
         }
         const comment = reader.readMatch('/*');
         if (!comment) break;
@@ -3457,11 +3006,10 @@ self.parserlib = (() => {
       const value = this.readNumber(first);
       let tt = Tokens.NUMBER;
       let units, type;
-
       const c = reader.peek();
-      if (isIdentStart(c)) {
+      if (stickyTest(rxIdentStart, 0, c)) {
         units = this.readName(reader.read());
-        type = UNITS[units] || UNITS[lower(units)];
+        type = UNITS[lower(units)];
         tt = type && Tokens[type.toUpperCase()] ||
              type === 'frequency' && Tokens.FREQ ||
              Tokens.DIMENSION;
@@ -3472,7 +3020,6 @@ self.parserlib = (() => {
       } else {
         type = 'number';
       }
-
       const token = this.createToken(tt, units ? value + units : value, pos);
       token.number = parseFloat(value);
       if (units) token.units = units;
@@ -3487,12 +3034,11 @@ self.parserlib = (() => {
       const string = first ? [first] : [];
       const reader = this._reader;
       let tt = Tokens.STRING;
-      let c = reader.read();
-      let i;
-
-      while (c) {
+      let c;
+      while (true) {
+        c = reader.readMatch(/[^\n\r\f\\'"]+|./y);
+        if (!c) break;
         string.push(c);
-
         if (c === '\\') {
           c = reader.read();
           if (c == null) {
@@ -3501,47 +3047,26 @@ self.parserlib = (() => {
             // single-character escape
             string.push(c);
           } else {
-            // read up to six hex digits
-            for (i = 0; isHexDigit(c) && i < 6; i++) {
-              string.push(c);
-              c = reader.read();
-            }
-            // swallow trailing newline or space
-            if (c === '\r' && reader.peek() === '\n') {
-              string.push(c);
-              c = reader.read();
-            }
-            if (isWhitespace(c)) {
-              string.push(c);
-            } else {
-              // This character is null or not part of the escape;
-              // jump back to the top to process it.
-              continue;
-            }
+            // read up to six hex digits + newline
+            string.push(c, reader.readMatch(/[0-9a-f]{1,6}\n?/yi));
           }
         } else if (c === delim) {
           break; // delimiter found.
-        } else if (isNewLine(reader.peek())) {
+        } else if (reader.peekTest(/[\n\r\f]/y)) {
           // newline without an escapement: it's an invalid string
           tt = Tokens.INVALID;
           break;
         }
-        c = reader.read();
       }
-
       // the string was never closed
       if (!c) tt = Tokens.INVALID;
-
-      return this.createToken(tt, string.join(''), pos);
+      return this.createToken(tt, fastJoin(string), pos);
     }
 
     // UNICODE_RANGE
     // CHAR
     unicodeRangeToken(first, pos) {
       const reader = this._reader;
-      if (reader.peek() !== '+') {
-        return this.createToken(Tokens.CHAR, first, pos);
-      }
       reader.mark();
       reader.read();
       let value = first + '+';
@@ -3565,15 +3090,10 @@ self.parserlib = (() => {
       return this.createToken(Tokens.UNICODE_RANGE, value, pos);
     }
 
-    // S
     whitespaceToken(first, pos) {
       return this.createToken(Tokens.S, first + this.readWhitespace(), pos);
     }
 
-    //-------------------------------------------------------------------------
-    // Methods to read values from the string stream
-    //-------------------------------------------------------------------------
-
     readUnicodeRangePart(allowQuestionMark) {
       const reader = this._reader;
       let part = reader.readMatch(/[0-9a-f]{1,6}/iy);
@@ -3593,15 +3113,15 @@ self.parserlib = (() => {
       const tail = this._reader.readMatch(
         first === '.' ?
           /\d+(e[+-]?\d+)?/iy :
-        isDigit(first) ?
+        first >= '0' && first <= '9' ?
           /\d*\.?\d*(e[+-]?\d+)?/iy :
           /(\d*\.\d+|\d+\.?\d*)(e[+-]?\d+)?/iy);
       return first + (tail || '');
     }
 
     // returns null w/o resetting reader if string is invalid.
-    readString() {
-      const token = this.stringToken(this._reader.read(), 0, 0);
+    readString(first = this._reader.read()) {
+      const token = this.stringToken(first, 0);
       return token.type !== Tokens.INVALID ? token.value : null;
     }
 
@@ -3610,31 +3130,29 @@ self.parserlib = (() => {
       const reader = this._reader;
       const uri = first;
       let value = '';
-
       this.readWhitespace();
-
-      if (/['"]/.test(reader.peek())) {
+      if (reader.peekTest(/['"]/y)) {
         value = this.readString();
         if (value == null) return null;
         value = parseString(value);
       } else {
         value = this.readUnquotedURL();
       }
-
       this.readWhitespace();
-      if (reader.peek() !== ')') return null;
-
       // Ensure argument to URL is always double-quoted
       // (This simplifies later processing in PropertyValuePart.)
-      return {value, text: uri + serializeString(value) + reader.read()};
+      return reader.peek() !== ')' ? null : {
+        value,
+        text: uri + serializeString(value) + reader.read(),
+      };
     }
 
     readUnquotedURL(first) {
-      return this.readChunksWithEscape(first, /[-!#$%&*-[\]-~\u00A0-\uFFFF]+/y);
+      return this.readChunksWithEscape(first, rxUnquotedUrlChar);
     }
 
     readName(first) {
-      return this.readChunksWithEscape(first, /[-_\da-zA-Z\u00A0-\uFFFF]+/y);
+      return this.readChunksWithEscape(first, rxNameChar);
     }
 
     readEscape() {
@@ -3648,17 +3166,14 @@ self.parserlib = (() => {
       while (true) {
         const chunk = reader.readMatch(rx);
         if (chunk) url.push(chunk);
-        if (reader.peek() === '\\' && /^[^\r\n\f]$/.test(reader.peek(2))) {
-          url.push(this.readEscape(reader.read()));
+        if (reader.peekTest(/\\[^\r\n\f]/y)) {
+          reader.read();
+          url.push(this.readEscape());
         } else {
           break;
         }
       }
-      return (
-        url.length > 2 ? url.join('') :
-        url.length > 1 ? url[0] + url[1] :
-        url[0] || ''
-      );
+      return fastJoin(url);
     }
 
     readComment(first) {
@@ -3668,8 +3183,8 @@ self.parserlib = (() => {
     }
   }
 
-  //endregion
-  //region parserCache
+  //#endregion
+  //#region parserCache
 
   /**
    * Caches the results and reuses them on subsequent parsing of the same code
@@ -3677,7 +3192,6 @@ self.parserlib = (() => {
   const parserCache = (() => {
     const MAX_DURATION = 10 * 60e3;
     const TRIM_DELAY = 10e3;
-
     // all blocks since page load; key = text between block start and { inclusive
     const data = new Map();
     // nested block stack
@@ -3693,130 +3207,120 @@ self.parserlib = (() => {
     let stream = null;
 
     return {
-      start,
-      addEvent,
-      findBlock,
-      startBlock,
-      adjustBlockStart,
-      endBlock,
-      cancelBlock: () => stack.pop(),
-      feedback,
-    };
-
-    /**
-     * Enables caching on the provided parser
-     * @param {Parser} newParser - use a falsy value to disable
-     */
-    function start(newParser) {
-      parser = newParser;
-      if (!parser) {
-        data.clear();
-        stack.length = 0;
-        generationBase = performance.now();
-        return;
-      }
-      if (firstRun) firstRun = false;
-      stream = parser._tokenStream;
-      generation = performance.now();
-      trim();
-    }
-
-    /**
-     * Adds the event into a matching nested open block which is currently being processed by the parser.
-     * @param {{offset, ...}} event - the event's `offset` property is used to determine the matching block
-     */
-    function addEvent(event) {
-      if (!parser) return;
-      for (let i = stack.length; --i >= 0;) {
-        const {offset, endOffset, events} = stack[i];
-        if (event.offset >= offset && (!endOffset || event.offset <= endOffset)) {
-          events.push(event);
+      start(newParser) {
+        parser = newParser;
+        if (!parser) {
+          data.clear();
+          stack.length = 0;
+          generationBase = performance.now();
           return;
         }
-      }
-    }
+        if (firstRun) firstRun = false;
+        stream = parser._tokenStream;
+        generation = performance.now();
+        trim();
+      },
+      addEvent(event) {
+        if (!parser) return;
+        for (let i = stack.length; --i >= 0;) {
+          const {offset, endOffset, events} = stack[i];
+          if (event.offset >= offset && (!endOffset || event.offset <= endOffset)) {
+            events.push(event);
+            return;
+          }
+        }
+      },
+      findBlock(token = getToken()) {
+        if (!parser || firstRun || !token) return;
 
-    /**
-     * Starts a nested block so it can accumulate subsequent events
-     * @param {(Token|SyntaxUnit)} [start = TokenStream::LT(1)]
-     */
-    function startBlock(start = getToken()) {
-      if (!parser) return;
-      stack.push({
-        text: '',
-        events: [],
-        generation: generation,
-        startLine: start.startLine || start.line,
-        startCol: start.startCol || start.col,
-        offset: start.offset,
-        endLine: undefined,
-        endCol: undefined,
-        endOffset: undefined,
-      });
-    }
+        const reader = stream._reader;
+        const input = reader._input;
+        let start = token.offset;
+        const c = input[start];
+        if (c === ' ' || c === '\t' || c === '\n' || c === '\f' || c === '\r') {
+          const rx = /\s*/y;
+          rx.lastIndex = start;
+          rx.exec(input);
+          start = rx.lastIndex;
+        }
+        const key = input.slice(start, input.indexOf('{', start) + 1);
+        const blocks = data.get(key);
+        if (!blocks) return;
 
-    /**
-     * Adjusts the start position of an already started block
-     * @param {(Token|SyntaxUnit)} [start = TokenStream::LT(1)]
-     */
-    function adjustBlockStart(start = getToken()) {
-      if (!parser) return;
-      const block = stack[stack.length - 1];
-      block.startLine = start.startLine || start.line;
-      block.startCol = start.startCol || start.col;
-      block.offset = start.offset;
-    }
+        const block = getBlock(blocks, input, start, key);
+        if (!block) return;
 
-    /**
-     * Closes the last opened block at the specified position and stores it in the cache
-     * @param {(Token|SyntaxUnit)} [token = TokenStream::LT(1)]
-     */
-    function endBlock(end = getToken()) {
-      if (!parser) return;
-      const block = stack.pop();
-      block.endLine = end.startLine || end.line;
-      block.endCol = (end.startCol || end.col) + end.value.length;
-      block.endOffset = end.offset + end.value.length;
+        reader.readCount(start - reader._cursor);
+        shiftBlock(reader, start, block);
+        shiftStream(reader, block);
+        parser._ws();
+        return true;
+      },
+      startBlock(start = getToken()) {
+        if (!parser) return;
+        stack.push({
+          text: '',
+          events: [],
+          generation: generation,
+          line: start.line,
+          col: start.col,
+          offset: start.offset,
+          endLine: undefined,
+          endCol: undefined,
+          endOffset: undefined,
+        });
+      },
+      adjustBlockStart(start = getToken()) {
+        if (!parser) return;
+        const block = stack[stack.length - 1];
+        block.line = start.line;
+        block.col = start.col;
+        block.offset = start.offset;
+      },
+      endBlock(end = getToken()) {
+        if (!parser) return;
+        const block = stack.pop();
+        block.endLine = end.line;
+        block.endCol = end.col + end.value.length;
+        block.endOffset = end.offset + end.value.length;
 
-      const input = stream._reader._input;
-      const key = input.slice(block.offset, input.indexOf('{', block.offset) + 1);
-      block.text = input.slice(block.offset, block.endOffset);
+        const input = stream._reader._input;
+        const key = input.slice(block.offset, input.indexOf('{', block.offset) + 1);
+        block.text = input.slice(block.offset, block.endOffset);
 
-      let blocks = data.get(key);
-      if (!blocks) data.set(key, (blocks = []));
-      blocks.push(block);
-    }
-
-    /**
-     * Tries to find a cached block that matches the input text at specified token's position.
-     * The nearest matching block is used to advance the parser's stream and reader.
-     * @param {(Token|SyntaxUnit)} [token = TokenStream::LT(1)]
-     */
-    function findBlock(token = getToken()) {
-      if (!parser || firstRun || !token) return;
-
-      const reader = stream._reader;
-      const input = reader._input;
-      let start = token.offset;
-      if (isWhitespace(input[start])) {
-        const rx = /\s*/y;
-        rx.lastIndex = start;
-        rx.exec(input);
-        start = rx.lastIndex;
-      }
-      const key = input.slice(start, input.indexOf('{', start) + 1);
-      const blocks = data.get(key);
-      if (!blocks) return;
-
-      const block = getBlock(blocks, input, start, key);
-      if (!block) return;
-
-      reader.readCount(start - reader._cursor);
-      shiftBlock(reader, start, block);
-      shiftStream(reader, block);
-      parser._ws();
-      return true;
-    }
+        let blocks = data.get(key);
+        if (!blocks) data.set(key, (blocks = []));
+        blocks.push(block);
+      },
+      cancelBlock: () => stack.pop(),
+      feedback({messages}) {
+        messages = new Set(messages);
+        for (const blocks of data.values()) {
+          for (const block of blocks) {
+            if (!block.events.length) continue;
+            if (block.generation !== generation) continue;
+            const {
+              line: L1,
+              col: C1,
+              endLine: L2,
+              endCol: C2,
+            } = block;
+            let isClean = true;
+            for (const msg of messages) {
+              const {line, col} = msg;
+              if (L1 === L2 && line === L1 && C1 <= col && col <= C2 ||
+                line === L1 && col >= C1 ||
+                line === L2 && col <= C2 ||
+                line > L1 && line < L2) {
+                messages.delete(msg);
+                isClean = false;
+              }
+            }
+            if (isClean) block.events.length = 0;
+          }
+        }
+      },
+    };
 
     /**
      * Removes old entries from the cache.
@@ -3844,40 +3348,6 @@ self.parserlib = (() => {
       }
     }
 
-    /**
-     * Uses the provided CSSLint report to decide which blocks should keep their events.
-     * Blocks that didn't cause any messages in CSSLint's rules report are stripped of their events.
-     * @param {{line, col, ...}[]} messages
-     * @todo retain stats and rollups in the report
-     */
-    function feedback({messages}) {
-      messages = new Set(messages);
-      for (const blocks of data.values()) {
-        for (const block of blocks) {
-          if (!block.events.length) continue;
-          if (block.generation !== generation) continue;
-          const {
-            startLine: L1,
-            startCol: C1,
-            endLine: L2,
-            endCol: C2,
-          } = block;
-          let isClean = true;
-          for (const msg of messages) {
-            const {line, col} = msg;
-            if (L1 === L2 && line === L1 && C1 <= col && col <= C2 ||
-                line === L1 && col >= C1 ||
-                line === L2 && col <= C2 ||
-                line > L1 && line < L2) {
-              messages.delete(msg);
-              isClean = false;
-            }
-          }
-          if (isClean) block.events.length = 0;
-        }
-      }
-    }
-
     // gets the matching block
     function getBlock(blocks, input, start, key) {
       // extracted to prevent V8 deopt
@@ -3905,23 +3375,23 @@ self.parserlib = (() => {
     // Shifts positions of the block and its events, also fires the events
     function shiftBlock(reader, start, block) {
       // extracted to prevent V8 deopt
-      const deltaLines = reader._line - block.startLine;
-      const deltaCols = block.startCol === 1 && reader._col === 1 ? 0 : reader._col - block.startCol;
+      const deltaLines = reader._line - block.line;
+      const deltaCols = block.col === 1 && reader._col === 1 ? 0 : reader._col - block.col;
       const deltaOffs = reader._cursor - block.offset;
       const hasDelta = deltaLines || deltaCols || deltaOffs;
       const shifted = new Set();
       for (const e of block.events) {
         if (hasDelta) {
-          applyDelta(e, shifted, block.startLine, deltaLines, deltaCols, deltaOffs);
+          applyDelta(e, shifted, block.line, deltaLines, deltaCols, deltaOffs);
         }
         parser.fire(e, false);
       }
       block.generation = generation;
-      block.endCol += block.endLine === block.startLine ? deltaCols : 0;
+      block.endCol += block.endLine === block.line ? deltaCols : 0;
       block.endLine += deltaLines;
       block.endOffset = reader._cursor + block.text.length;
-      block.startLine += deltaLines;
-      block.startCol += deltaCols;
+      block.line += deltaLines;
+      block.col += deltaCols;
       block.offset = reader._cursor;
     }
 
@@ -3930,20 +3400,17 @@ self.parserlib = (() => {
       reader._col = block.endCol;
       reader._cursor = block.endOffset;
 
-      stream._lt.length = 0;
-      stream._ltIndexCache.length = 0;
-      stream._ltIndex = 0;
-      stream._token = undefined;
+      stream.resetLT();
     }
 
     // Recursively applies the delta to the event and all its nested parts
-    function applyDelta(obj, seen, startLine, lines, cols, offs) {
+    function applyDelta(obj, seen, line, lines, cols, offs) {
       if (seen.has(obj)) return;
       seen.add(obj);
       if (Array.isArray(obj)) {
         for (const item of obj) {
           if ((typeof item === 'object' || Array.isArray(item)) && item) {
-            applyDelta(item, seen, startLine, lines, cols, offs);
+            applyDelta(item, seen, line, lines, cols, offs);
           }
         }
         return;
@@ -3952,53 +3419,48 @@ self.parserlib = (() => {
       // because in js an array lookup is much faster than a property lookup
       const keys = Object.keys(obj);
       if (cols !== 0) {
-        if (keys.includes('startCol') && obj.startLine === startLine) obj.col += cols;
-        if (keys.includes('endCol') && obj.endLine === startLine) obj.endCol += cols;
-        if (keys.includes('col') && obj.line === startLine) obj.col += cols;
+        if (keys.includes('col') && obj.line === line) obj.col += cols;
+        if (keys.includes('endCol') && obj.endLine === line) obj.endCol += cols;
       }
       if (lines !== 0) {
         if (keys.includes('line')) obj.line += lines;
         if (keys.includes('endLine')) obj.endLine += lines;
-        if (keys.includes('startLine')) obj.startLine += lines;
       }
       if (offs !== 0 && keys.includes('offset')) obj.offset += offs;
       for (const k of keys) {
-        if (k !== 'col' && k !== 'startCol' && k !== 'endCol' &&
-            k !== 'line' && k !== 'startLine' && k !== 'endLine' &&
+        if (k !== 'col' && k !== 'endCol' &&
+            k !== 'line' && k !== 'endLine' &&
             k !== 'offset') {
           const v = obj[k];
           if (v && typeof v === 'object') {
-            applyDelta(v, seen, startLine, lines, cols, offs);
+            applyDelta(v, seen, line, lines, cols, offs);
           }
         }
       }
     }
 
-    // returns TokenStream::LT(1) or null
+    // returns next token if it's already seen or the current token
     function getToken() {
-      return parser ?
-        stream._lt[stream._ltIndex] || stream._token :
-        null;
+      return parser && (stream.LT(1, true) || stream._token);
     }
 
     function deepCopy(obj) {
-      if (!obj || typeof obj !== 'object') return obj;
+      if (!obj || typeof obj !== 'object') {
+        return obj;
+      }
       if (Array.isArray(obj)) {
-        return obj.map(v => !v || typeof v !== 'object' ? v : deepCopy(v));
+        return obj.map(deepCopy);
       }
       const copy = {};
-      const hasOwnProperty = Object.prototype.hasOwnProperty;
-      for (const k in obj) {
-        if (!hasOwnProperty.call(obj, k)) continue;
-        const v = obj[k];
-        copy[k] = !v || typeof v !== 'object' ? v : deepCopy(v);
+      for (const [k, v] of Object.entries(obj)) {
+        copy[k] = deepCopy(v);
       }
       return copy;
     }
   })();
 
-  //endregion
-  //region Parser
+  //#endregion
+  //#region Parser
 
   class Parser extends EventTarget {
     /**
@@ -4006,10 +3468,13 @@ self.parserlib = (() => {
      * @param {Boolean} [options.starHack] - allows IE6 star hack
      * @param {Boolean} [options.underscoreHack] - interprets leading underscores as IE6-7 for known properties
      * @param {Boolean} [options.ieFilters] - accepts IE < 8 filters instead of throwing syntax errors
+     * @param {Boolean} [options.strict] - stop on errors instead of reporting them and continuing
+     * @param {Boolean} [options.skipValidation] - skip syntax validation
      */
     constructor(options) {
       super();
       this.options = options || {};
+      /** @type {TokenStream|TokenStreamBase} */
       this._tokenStream = null;
     }
 
@@ -4025,8 +3490,8 @@ self.parserlib = (() => {
       }
       if (event.offset === undefined && token) {
         event.offset = token.offset;
-        if (event.line === undefined) event.line = token.startLine || token.line;
-        if (event.col === undefined) event.col = token.startCol || token.col;
+        if (event.line === undefined) event.line = token.line;
+        if (event.col === undefined) event.col = token.col;
       }
       if (token !== false) parserCache.addEvent(event);
       super.fire(event);
@@ -4034,39 +3499,32 @@ self.parserlib = (() => {
 
     _stylesheet() {
       const stream = this._tokenStream;
-
       this.fire('startstylesheet');
-
-      this._charset();
       this._skipCruft();
-
-      while (stream.peek() === Tokens.IMPORT_SYM) {
-        this._import();
-        this._skipCruft();
+      for (const [type, fn, max = Infinity] of [
+        [Tokens.CHARSET_SYM, this._charset, 1],
+        [Tokens.IMPORT_SYM, this._import],
+        [Tokens.NAMESPACE_SYM, this._namespace],
+      ]) {
+        for (let i = 0; i++ < max && stream.peek() === type;) {
+          fn.call(this, stream.get(true));
+          this._skipCruft();
+        }
       }
-
-      while (stream.peek() === Tokens.NAMESPACE_SYM) {
-        this._namespace();
-        this._skipCruft();
-      }
-
-      for (let tt; (tt = stream.peek()) > Tokens.EOF; this._skipCruft()) {
+      for (let tt, token; (tt = (token = stream.LT(1)).type) > Tokens.EOF; this._skipCruft()) {
         try {
           let action = Parser.ACTIONS.stylesheet.get(tt);
           if (action) {
-            action.call(this);
+            action.call(this, stream.get(true));
             continue;
           }
           action = Parser.ACTIONS.stylesheetMisplaced.get(tt);
           if (action) {
-            const token = stream.LT(1);
-            action.call(this, false);
+            action.call(this, stream.get(true), true);
             throw new SyntaxError(Tokens[tt].text + ' not allowed here.', token);
           }
-          if (this._ruleset()) continue;
-          if (stream.peek() !== Tokens.EOF) {
-            stream.get();
-            this._unexpectedToken(stream._token);
+          if (!this._ruleset() && stream.peek() !== Tokens.EOF) {
+            stream.throwUnexpected(stream.get(true));
           }
         } catch (ex) {
           if (ex instanceof SyntaxError && !this.options.strict) {
@@ -4076,104 +3534,69 @@ self.parserlib = (() => {
           }
         }
       }
-
       this.fire('endstylesheet');
     }
 
-    _charset(emit = true) {
+    _charset(start, misplaced) {
       const stream = this._tokenStream;
-      if (!stream.match(Tokens.CHARSET_SYM)) return;
-      const start = stream._token;
       const charset = stream.mustMatch(Tokens.STRING).value;
       stream.mustMatch(Tokens.SEMICOLON);
-      if (emit) {
-        this.fire({
-          type: 'charset',
-          charset,
-        }, start);
-      }
+      if (!misplaced) this.fire({type: 'charset', charset}, start);
     }
 
-    _import(emit = true) {
+    _import(start, misplaced) {
       const stream = this._tokenStream;
-      const start = stream.mustMatch(Tokens.IMPORT_SYM);
-      stream.mustMatch(TT.stringUri);
-      const uri = stream._token.value.replace(/^(?:url\()?["']?([^"']+?)["']?\)?$/, '$1');
+      const token = stream.mustMatch(TT.stringUri);
+      const uri = token.uri || token.value.replace(/^["']|["']$/g, '');
       this._ws();
-      const mediaList = this._mediaQueryList();
+      const media = this._mediaQueryList();
       stream.mustMatch(Tokens.SEMICOLON);
-      if (emit) {
-        this.fire({
-          type: 'import',
-          media: mediaList,
-          uri,
-        }, start);
-      }
+      if (!misplaced) this.fire({type: 'import', media, uri}, start);
       this._ws();
     }
 
-    _namespace(emit = true) {
+    _namespace(start, misplaced) {
       const stream = this._tokenStream;
-      const start = stream.mustMatch(Tokens.NAMESPACE_SYM);
-      let prefix = null;
       this._ws();
-      if (stream.match(Tokens.IDENT)) {
-        prefix = stream._token.value;
-        this._ws();
-      }
-      stream.mustMatch(TT.stringUri);
-      const uri = stream._token.value.replace(/(?:url\()?["']([^"']+)["']\)?/, '$1');
+      const prefix = stream.match(Tokens.IDENT).value;
+      if (prefix) this._ws();
+      const token = stream.mustMatch(TT.stringUri);
+      const uri = token.uri || token.value.replace(/^["']|["']$/g, '');
       stream.mustMatch(Tokens.SEMICOLON);
-      if (emit) {
-        this.fire({
-          type: 'namespace',
-          prefix,
-          uri,
-        }, start);
-      }
+      if (!misplaced) this.fire({type: 'namespace', prefix, uri}, start);
       this._ws();
     }
 
-    _supports(emit = true) {
+    _supports(start, misplaced) {
       const stream = this._tokenStream;
-      if (!stream.match(Tokens.SUPPORTS_SYM)) return;
-
-      const start = stream._token;
       this._ws();
       this._supportsCondition();
       stream.mustMatch(Tokens.LBRACE);
-      if (emit) this.fire('startsupports', start);
+      if (!misplaced) this.fire('startsupports', start);
       this._ws();
-
       for (;; stream.skipComment()) {
         const action = Parser.ACTIONS.supports.get(stream.peek());
         if (action) {
-          action.call(this);
+          action.call(this, stream.get(true));
         } else if (!this._ruleset()) {
           break;
         }
       }
-
       stream.mustMatch(Tokens.RBRACE);
-      if (emit) this.fire('endsupports');
+      if (!misplaced) this.fire('endsupports');
       this._ws();
     }
 
     _supportsCondition() {
       const stream = this._tokenStream;
-      const next = stream.LT(1);
-      if (next.type === Tokens.IDENT && lowerCmp(next.value, 'not')) {
-        stream.get();
+      if (stream.match(Tokens.IDENT, ['not'])) {
         stream.mustMatch(Tokens.S);
         this._supportsConditionInParens();
       } else {
         this._supportsConditionInParens();
-        while (stream.peek() === Tokens.IDENT) {
-          if (/^(and|or)$/i.test(stream.LT(1).value)) {
-            stream.get();
-            this._ws();
-            this._supportsConditionInParens();
-          }
+        while (stream.match(Tokens.IDENT, ['and', 'or'])) {
+          this._ws();
+          this._supportsConditionInParens();
         }
       }
     }
@@ -4196,8 +3619,7 @@ self.parserlib = (() => {
           this._supportsCondition();
           stream.mustMatch(Tokens.RPAREN);
         }
-      } else if (next.type === Tokens.FUNCTION && lowerCmp(next.value, 'selector(')) {
-        stream.get();
+      } else if (stream.match(Tokens.FUNCTION, ['selector('])) {
         this._ws();
         this._selector();
         stream.mustMatch(Tokens.RPAREN);
@@ -4217,23 +3639,19 @@ self.parserlib = (() => {
       stream.mustMatch(Tokens.RPAREN);
     }
 
-    _media() {
+    _media(start) {
       const stream = this._tokenStream;
-      const start = stream.mustMatch(Tokens.MEDIA_SYM);
       this._ws();
       const mediaList = this._mediaQueryList();
-
       stream.mustMatch(Tokens.LBRACE);
       this.fire({
         type: 'startmedia',
         media: mediaList,
       }, start);
       this._ws();
-
       let action;
       do action = Parser.ACTIONS.media.get(stream.peek());
-      while (action ? action.call(this) || true : this._ruleset());
-
+      while (action ? action.call(this, stream.get(true)) || true : this._ruleset());
       stream.mustMatch(Tokens.RBRACE);
       this.fire({
         type: 'endmedia',
@@ -4245,17 +3663,14 @@ self.parserlib = (() => {
     _mediaQueryList() {
       const stream = this._tokenStream;
       const mediaList = [];
-
       this._ws();
       if ([Tokens.IDENT, Tokens.LPAREN].includes(stream.peek())) {
         mediaList.push(this._mediaQuery());
       }
-
       while (stream.match(Tokens.COMMA)) {
         this._ws();
         mediaList.push(this._mediaQuery());
       }
-
       return mediaList;
     }
 
@@ -4263,23 +3678,19 @@ self.parserlib = (() => {
       const stream = this._tokenStream;
       const expressions = [];
       let type = null;
-      let token = stream.LT(1);
-      let ident = token.value;
-      if (token.type === Tokens.IDENT && /^(only|not)$/i.test(ident)) {
-        stream.get();
-      } else {
-        token = ident = null;
-      }
+      const token = stream.match(Tokens.IDENT, ['only', 'not']);
+      const ident = token.value || null;
       this._ws();
       const next = stream.LT(1);
-      if (next.type === Tokens.IDENT) {
-        token = token || next;
-        type = this._mediaFeature();
-      } else if (next.type === Tokens.LPAREN) {
-        token = token || next;
-        expressions.push(this._mediaExpression());
-      } else {
-        return;
+      switch (next.type) {
+        case Tokens.IDENT:
+          type = this._mediaFeature();
+          break;
+        case Tokens.LPAREN:
+          expressions.push(this._mediaExpression());
+          break;
+        default:
+          return;
       }
       this._ws();
       while (stream.match(Tokens.IDENT)) {
@@ -4287,10 +3698,10 @@ self.parserlib = (() => {
           this._ws();
           expressions.push(this._mediaExpression());
         } else {
-          this._unexpectedToken(stream._token);
+          stream.throwUnexpected(undefined, ["'and'"]);
         }
       }
-      return new MediaQuery(ident, type, expressions, token);
+      return new MediaQuery(ident, type, expressions, token || next);
     }
 
     _mediaExpression() {
@@ -4315,126 +3726,59 @@ self.parserlib = (() => {
       return SyntaxUnit.fromToken(this._tokenStream._token);
     }
 
-    _page() {
+    _page(start) {
       const stream = this._tokenStream;
-      let identifier = null;
-      let pseudoPage = null;
-
-      // look for @page
-      stream.mustMatch(Tokens.PAGE_SYM);
-      const start = stream._token;
-
       this._ws();
-
-      if (stream.match(Tokens.IDENT)) {
-        identifier = stream._token.value;
-
-        // The value 'auto' may not be used as a page name and MUST be treated as a syntax error.
-        if (lowerCmp(identifier, 'auto')) {
-          this._unexpectedToken(stream._token);
-        }
+      const id = stream.match(Tokens.IDENT).value || null;
+      if (id && lowerCmp(id, 'auto')) {
+        stream.throwUnexpected();
       }
-
-      // see if there's a colon upcoming
-      if (stream.peek() === Tokens.COLON) {
-        pseudoPage = this._pseudoPage();
-      }
-
+      const pseudo = stream.match(Tokens.COLON)
+        ? stream.mustMatch(Tokens.IDENT, false).value
+        : null;
       this._ws();
-
-      this.fire({
-        type:   'startpage',
-        id:     identifier,
-        pseudo: pseudoPage,
-      }, start);
-
+      this.fire({type: 'startpage', id, pseudo}, start);
       this._readDeclarations({readMargins: true});
-
-      this.fire({
-        type:   'endpage',
-        id:     identifier,
-        pseudo: pseudoPage,
-      });
+      this.fire({type: 'endpage', id, pseudo});
     }
 
     _margin() {
-      const margin = this._marginSym();
+      const margin = SyntaxUnit.fromToken(this._tokenStream.match(TT.margins));
       if (!margin) return false;
-
-      this.fire({
-        type: 'startpagemargin',
-        margin,
-      });
-
+      this.fire({type: 'startpagemargin', margin});
       this._readDeclarations();
-
-      this.fire({
-        type: 'endpagemargin',
-        margin,
-      });
-
+      this.fire({type: 'endpagemargin', margin});
       return true;
     }
 
-    _marginSym() {
-      if (this._tokenStream.match(TT.margins)) {
-        return SyntaxUnit.fromToken(this._tokenStream._token);
-      } else {
-        return null;
-      }
-    }
-
-    _pseudoPage() {
-      const stream = this._tokenStream;
-      stream.mustMatch(Tokens.COLON, false);
-      stream.mustMatch(Tokens.IDENT, false);
-      // TODO: CSS3 Paged Media says only "left", "center", and "right" are allowed
-      return stream._token.value;
-    }
-
-    _fontFace() {
-      const stream = this._tokenStream;
-      stream.mustMatch(Tokens.FONT_FACE_SYM);
-
-      this.fire('startfontface');
-
+    _fontFace(start) {
+      this.fire('startfontface', start);
       this._ws();
       this._readDeclarations();
-
       this.fire('endfontface');
     }
 
-    _viewport() {
-      const stream = this._tokenStream;
-      const start = stream.mustMatch(Tokens.VIEWPORT_SYM);
-
+    _viewport(start) {
       // only viewport-fit is allowed but we're reusing MediaQuery syntax unit,
       // and accept anything for the sake of simplicity since the spec isn't yet final:
       // https://drafts.csswg.org/css-round-display/#extending-viewport-rule
       const descriptors = this._mediaQueryList();
-
-      this.fire({
-        type: 'startviewport',
-        descriptors,
-      }, start);
-
+      this.fire({type: 'startviewport', descriptors}, start);
       this._ws();
       this._readDeclarations();
-
-      this.fire({
-        type: 'endviewport',
-        descriptors,
-      });
+      this.fire({type: 'endviewport', descriptors});
     }
 
-    _document() {
+    _document(start) {
       const stream = this._tokenStream;
       const functions = [];
-      const start = stream.mustMatch(Tokens.DOCUMENT_SYM);
       const prefix = start.value.split('-')[1] || '';
       do {
         this._ws();
-        functions.push(this._documentFunction() || stream.LT(1));
+        const uri = stream.match(Tokens.URI);
+        const fn = uri ? new PropertyValuePart(uri) : this._function() || stream.LT(1);
+        functions.push(fn);
+        if (uri) this._ws();
       } while (stream.match(Tokens.COMMA));
       for (const fn of functions) {
         if ((fn.type !== 'function' || !/^(url(-prefix)?|domain|regexp)$/i.test(fn.name)) &&
@@ -4447,92 +3791,55 @@ self.parserlib = (() => {
         }
       }
       stream.mustMatch(Tokens.LBRACE);
-
-      this.fire({
-        type: 'startdocument',
-        functions,
-        prefix,
-      }, start);
-
+      this.fire({type: 'startdocument', functions, prefix}, start);
       this._ws();
-
       let action;
       do action = Parser.ACTIONS.document.get(stream.peek());
-      while (action ? action.call(this) || true : this._ruleset());
-
+      while (action ? action.call(this, stream.get(true)) || true : this._ruleset());
       stream.mustMatch(Tokens.RBRACE);
-
-      this.fire({
-        type: 'enddocument',
-        functions,
-        prefix,
-      });
-
+      this.fire({type: 'enddocument', functions, prefix});
       this._ws();
     }
 
-    _documentMisplaced() {
+    _documentMisplaced(start) {
       this.fire({
-        type:    'error',
+        type: 'error',
         message: 'Nested @document produces broken code',
-      }, this._tokenStream.LT(1));
-      this._document();
-    }
-
-    _documentFunction() {
-      const stream = this._tokenStream;
-      if (stream.match(Tokens.URI)) {
-        const res = new PropertyValuePart(stream._token);
-        this._ws();
-        return res;
-      }
-      return this._function();
-    }
-
-    _operator(inFunction) {
-      if (this._tokenStream.match(inFunction ? TT.opInFunc : TT.op)) {
-        const value = new PropertyValuePart(this._tokenStream._token);
-        this._ws();
-        return value;
-      }
+      }, start);
+      this._document(start);
     }
 
     _combinator() {
-      if (this._tokenStream.match(TT.combinator)) {
-        const value = new Combinator(this._tokenStream._token);
+      const token = this._tokenStream.match(TT.combinator);
+      if (token) {
         this._ws();
-        return value;
+        return new Combinator(token);
       }
     }
 
     _property() {
       const stream = this._tokenStream;
+      let token = stream.get(true);
       let value = null;
       let hack = null;
-      let tokenValue, token, start;
-
-      // check for star hack - throws error if not allowed
-      if (stream.peek() === Tokens.STAR && this.options.starHack) {
-        stream.get();
-        token = stream._token;
+      let start;
+      if (this.options.starHack && token.type === Tokens.STAR) {
+        hack = '*';
         start = token;
-        hack = token.value;
+        token = stream.get(true);
       }
-
-      if (stream.match(TT.identCustom)) {
-        token = stream._token;
-        tokenValue = token.value;
-
+      if (token.type === Tokens.IDENT || token.type === Tokens.CUSTOM_PROP) {
+        let tokenValue = token.value;
         // check for underscore hack - no error if not allowed because it's valid CSS syntax
-        if (tokenValue.charAt(0) === '_' && this.options.underscoreHack) {
+        if (this.options.underscoreHack && tokenValue.startsWith('_')) {
           hack = '_';
-          tokenValue = tokenValue.substring(1);
+          tokenValue = tokenValue.slice(1);
         }
-
         value = new PropertyName(tokenValue, hack, start || token);
         this._ws();
+      } else {
+        stream.unget();
       }
-
       return value;
     }
 
@@ -4541,36 +3848,23 @@ self.parserlib = (() => {
       let braceOpened;
       try {
         stream.skipComment();
-
-        if (parserCache.findBlock()) return true;
+        if (parserCache.findBlock()) {
+          return true;
+        }
         parserCache.startBlock();
-
         const selectors = this._selectorsGroup();
         if (!selectors) {
           parserCache.cancelBlock();
           return false;
         }
-
         parserCache.adjustBlockStart(selectors[0]);
-
-        this.fire({
-          type: 'startrule',
-          selectors,
-        }, selectors[0]);
-
+        this.fire({type: 'startrule', selectors}, selectors[0]);
         this._readDeclarations({stopAfterBrace: true});
         braceOpened = true;
-
-        this.fire({
-          type: 'endrule',
-          selectors,
-        });
-
+        this.fire({type: 'endrule', selectors});
         parserCache.endBlock();
-
         this._ws();
         return true;
-
       } catch (ex) {
         parserCache.cancelBlock();
         if (!(ex instanceof SyntaxError) || this.options.strict) throw ex;
@@ -4585,204 +3879,164 @@ self.parserlib = (() => {
     }
 
     _selectorsGroup() {
+      const stream = this._tokenStream;
       const selectors = [];
-      let selector, comma;
-
-      while ((selector = this._selector())) {
-        selectors.push(selector);
-        this._ws(true);
-        comma = this._tokenStream.match(Tokens.COMMA);
+      let comma;
+      for (let sel; (sel = this._selector());) {
+        selectors.push(sel);
+        this._ws(null, true);
+        comma = stream.match(Tokens.COMMA);
         if (!comma) break;
-        this._ws(true);
+        this._ws(null, true);
       }
-
-      if (comma) this._unexpectedToken(this._tokenStream.LT(1));
-
+      if (comma) stream.throwUnexpected(stream.LT(1));
       return selectors.length ? selectors : null;
     }
 
     _selector() {
       const stream = this._tokenStream;
-      const selector = [];
-      let nextSelector = null;
+      const sel = [];
+      let nextSel = null;
       let combinator = null;
-
-      nextSelector = this._simpleSelectorSequence();
-      if (!nextSelector) return null;
-
-      selector.push(nextSelector);
-
+      nextSel = this._simpleSelectorSequence();
+      if (!nextSel) {
+        return null;
+      }
+      sel.push(nextSel);
       while (true) {
         combinator = this._combinator();
-
         if (combinator) {
-          selector.push(combinator);
-          nextSelector = this._simpleSelectorSequence();
-          if (nextSelector) {
-            selector.push(nextSelector);
+          sel.push(combinator);
+          nextSel = this._simpleSelectorSequence();
+          if (nextSel) {
+            sel.push(nextSel);
             continue;
           }
-          this._unexpectedToken(stream.LT(1));
+          stream.throwUnexpected(stream.LT(1));
+          break;
+        }
+        if (!this._ws(null, true)) {
           break;
         }
-
-        if (!this._ws(true)) break;
-
         // make a fallback whitespace combinator
         const ws = new Combinator(stream._token);
         // look for an explicit combinator
         combinator = this._combinator();
-
         // selector is required if there's a combinator
-        nextSelector = this._simpleSelectorSequence();
-        if (nextSelector) {
-          selector.push(combinator || ws);
-          selector.push(nextSelector);
+        nextSel = this._simpleSelectorSequence();
+        if (nextSel) {
+          sel.push(combinator || ws);
+          sel.push(nextSel);
         } else if (combinator) {
-          this._unexpectedToken(stream.LT(1));
+          stream.throwUnexpected(stream.LT(1));
         }
       }
-
-      return new Selector(selector, selector[0]);
+      return new Selector(sel, sel[0]);
     }
 
     _simpleSelectorSequence() {
       const stream = this._tokenStream;
-      const start = stream._lt[stream._ltIndex] || stream.LT(1);
+      const start = stream.LT(1);
       const modifiers = [];
-      let text = '';
-
-      const ns = this._namespacePrefix();
+      const seq = [];
+      const ns = this._namespacePrefix(start.type);
       const elementName = this._typeSelector(ns) || this._universal(ns);
       if (elementName) {
-        text += elementName;
+        seq.push(elementName);
       } else if (ns) {
         stream.unget();
       }
-
       while (true) {
-        const action = Parser.ACTIONS.simpleSelectorSequence.get(stream.peek());
-        const component = action && action.call(this);
+        const token = stream.get(true);
+        const action = Parser.ACTIONS.simpleSelectorSequence.get(token.type);
+        const component = action ? action.call(this, token) : (stream.unget(), 0);
         if (!component) break;
         modifiers.push(component);
-        text += component;
+        seq.push(component);
       }
-
+      const text = fastJoin(seq);
       return text && new SelectorPart(elementName, modifiers, text, start);
     }
 
     _typeSelector(ns) {
       const stream = this._tokenStream;
       const nsSupplied = ns !== undefined;
-      ns = nsSupplied ? ns : this._namespacePrefix();
-      const elementName = this._elementName();
-
-      if (!elementName) {
+      if (!nsSupplied) ns = this._namespacePrefix();
+      const name = stream.match(Tokens.IDENT) &&
+        new SelectorSubPart(stream._token.value, 'elementName', stream._token);
+      if (!name) {
         if (!nsSupplied && ns && ns.length > 0) stream.unget();
         if (!nsSupplied && ns && ns.length > 1) stream.unget();
         return null;
       }
-
       if (ns) {
-        elementName.text = ns + elementName.text;
-        elementName.col -= ns.length;
+        name.text = ns + name.text;
+        name.col -= ns.length;
       }
-      return elementName;
+      return name;
     }
 
-    _hash() {
+    _hash(start) {
+      return new SelectorSubPart(start.value, 'id', start);
+    }
+
+    _class(start) {
+      const name = this._tokenStream.mustMatch(Tokens.IDENT, false).value;
+      return new SelectorSubPart('.' + name, 'class', start);
+    }
+
+    _namespacePrefix(next) {
       const stream = this._tokenStream;
-      if (!stream.match(Tokens.HASH)) return null;
-      return new SelectorSubPart(stream._token.value, 'id', stream._token);
-    }
-
-    _class() {
-      if (!this._tokenStream.match(Tokens.DOT)) return null;
-      this._tokenStream.mustMatch(Tokens.IDENT, false);
-      const {value, startLine: line, startCol: col, offset} = this._tokenStream._token;
-      return new SelectorSubPart('.' + value, 'class', {line, col: col - 1, offset});
-    }
-
-    _elementName() {
-      const stream = this._tokenStream;
-      if (!stream.match(Tokens.IDENT)) return null;
-      return new SelectorSubPart(stream._token.value, 'elementName', stream._token);
-    }
-
-    _namespacePrefix() {
-      const stream = this._tokenStream;
-      const lt = stream._lt;
-      const i = stream._ltIndex;
-      if ((i < lt.length && lt[i].type || stream.LA(1)) !== Tokens.PIPE &&
-          (i + 1 < lt.length && lt[i + 1].type || stream.LA(2)) !== Tokens.PIPE) {
-        return null;
-      }
-      return (stream.match(TT.ns).value || '') + stream.mustMatch(Tokens.PIPE, false).value;
+      if (!next) next = stream.LA(1);
+      return next === Tokens.PIPE ? '|' :
+        (next === Tokens.IDENT || next === Tokens.STAR) && stream.LA(2) === Tokens.PIPE
+          ? stream.get().value + stream.get().value
+          : null;
     }
 
     _universal(ns = this._namespacePrefix()) {
       return `${ns || ''}${this._tokenStream.match(Tokens.STAR).value || ''}` || null;
     }
 
-    _attrib() {
+    _attrib(start) {
       const stream = this._tokenStream;
-      if (!stream.match(Tokens.LBRACKET)) return null;
-      const start = stream._token;
-      let value = start.value +
-        this._ws() +
-        (this._namespacePrefix() || '') +
-        stream.mustMatch(Tokens.IDENT, false).value +
-        this._ws();
+      const value = [
+        start.value,
+        this._ws(),
+        this._namespacePrefix() || '',
+        stream.mustMatch(Tokens.IDENT, false).value,
+        this._ws(),
+      ];
       if (stream.match(TT.attrMatch)) {
-        value += stream._token.value + this._ws() +
-          stream.mustMatch(TT.identString).value +
-          this._ws();
-        const next = stream.LT(1);
-        if (next.type === Tokens.IDENT && /^[is]$/i.test(next.value)) {
-          stream.get();
-          value += next.value + this._ws();
+        value.push(
+          stream._token.value,
+          this._ws(),
+          stream.mustMatch(TT.identString).value,
+          this._ws());
+        if (stream.match(Tokens.IDENT, ['i', 's'])) {
+          value.push(
+            stream._token.value,
+            this._ws());
         }
       }
-      stream.mustMatch(Tokens.RBRACKET);
-      return new SelectorSubPart(value + ']', 'attribute', start);
+      value.push(stream.mustMatch(Tokens.RBRACKET).value);
+      return new SelectorSubPart(fastJoin(value), 'attribute', start);
     }
 
-    _pseudo() {
+    _pseudo(start) {
       const stream = this._tokenStream;
-      let pseudo = null;
-      let colons = ':';
-      let line, col, offset;
-
-      // read 1 or 2 colons
-      if (!stream.match(Tokens.COLON)) return null;
-      if (stream.match(Tokens.COLON)) colons += ':';
-
-      if (stream.match(Tokens.IDENT)) {
-        pseudo = stream._token.value;
-        line = stream._token.startLine;
-        col = stream._token.startCol - colons.length;
-        offset = stream._token.offset - colons.length;
-      } else if (stream.peek() === Tokens.FUNCTION) {
-        line = stream.LT(1).startLine;
-        col = stream.LT(1).startCol - colons.length;
-        offset = stream.LT(1).offset - colons.length;
-        if (stream.match(Tokens.FUNCTION)) {
-          pseudo =
-            stream._token.value +
-            this._ws() +
-            (this._expression({list: true}) || '') +
-            ')';
-          stream.mustMatch(Tokens.RPAREN);
-        }
-      }
-
-      if (pseudo) return new SelectorSubPart(colons + pseudo, 'pseudo', {line, col, offset});
-
-      const startLine = stream.LT(1).startLine;
-      const startCol = stream.LT(0).startCol;
-      throw new SyntaxError(
-        `Expected a 'FUNCTION' or 'IDENT' after colon at line ${startLine}, col ${startCol}.`,
-        {startLine, startCol});
+      const colons = start.value + (stream.match(Tokens.COLON).value || '');
+      const t = stream.mustMatch(TT.pseudo);
+      const pseudo = t.type === Tokens.IDENT ? t.value :
+        t.value +
+        this._ws() +
+        (this._expression({list: true}) || '') +
+        stream.mustMatch(Tokens.RPAREN).value;
+      return new SelectorSubPart(colons + pseudo, 'pseudo', {
+        line: t.line,
+        col: t.col - colons.length,
+        offset: t.offset - colons.length,
+      });
     }
 
     _expression({calc, list} = {}) {
@@ -4791,7 +4045,9 @@ self.parserlib = (() => {
       while (stream.get()) {
         const {type, value} = stream._token;
         if (calc && type === Tokens.FUNCTION) {
-          if (!RX_CALC.test(value)) this._unexpectedToken();
+          if (!rxCalc.test(value)) {
+            stream.throwUnexpected();
+          }
           chunks.push(value,
             this._expr('calc').text,
             stream.mustMatch(Tokens.RPAREN).value);
@@ -4802,130 +4058,97 @@ self.parserlib = (() => {
           break;
         }
       }
-      return chunks.length ? chunks.join('') : null;
+      return fastJoin(chunks) || null;
     }
 
-    _is() {
-      const stream = this._tokenStream;
-      if (!stream.match([Tokens.IS, Tokens.ANY, Tokens.WHERE])) return null;
-
-      let arg;
-      const start = stream._token;
-      const type = lower(Tokens[start.type].name);
+    _is(start) {
+      let args;
       const value =
         start.value +
         this._ws() +
-        ((arg = this._selectorsGroup())) +
+        (args = this._selectorsGroup()) +
         this._ws() +
-        ')';
-      stream.mustMatch(Tokens.RPAREN);
-
-      const subpart = new SelectorSubPart(value, type, start);
-      subpart.args = arg;
-      return subpart;
+        this._tokenStream.mustMatch(Tokens.RPAREN).value;
+      const type = lower(Tokens.name(start.type));
+      return Object.assign(new SelectorSubPart(value, type, start), {args});
     }
 
-    _negation() {
+    _negation(start) {
       const stream = this._tokenStream;
-      if (!stream.match(Tokens.NOT)) return null;
-
-      const start = stream._token;
       let value = start.value + this._ws();
-
-      const arg = this._selectorsGroup();
-      if (!arg) this._unexpectedToken(stream.LT(1));
-      const parts = arg[0].parts;
-      if (arg.length > 1 ||
+      const args = this._selectorsGroup();
+      if (!args) stream.throwUnexpected(stream.LT(1));
+      const arg = args[0];
+      const parts = arg.parts;
+      if (args.length > 1 ||
           parts.length !== 1 ||
           parts[0].modifiers.length + (parts[0].elementName ? 1 : 0) > 1 ||
           /^:not\b/i.test(parts[0])) {
         this.fire({
           type: 'warning',
-          message: `Simple selector expected, but found '${arg.join(', ')}'`,
-        }, arg[0]);
+          message: `Simple selector expected, but found '${args.join(', ')}'`,
+        }, arg);
       }
-      value += arg[0] + this._ws() + ')';
-      stream.mustMatch(Tokens.RPAREN);
-
-      const subpart = new SelectorSubPart(value, 'not', start);
-      subpart.args.push(arg[0]);
-      return subpart;
+      value += arg + this._ws() + stream.mustMatch(Tokens.RPAREN).value;
+      return Object.assign(new SelectorSubPart(value, 'not', start), {args: [arg]});
     }
 
     _declaration(consumeSemicolon) {
       const stream = this._tokenStream;
-
       const property = this._property();
       if (!property) {
         return false;
       }
-
       stream.mustMatch(Tokens.COLON);
-
-      let value = null;
-      // whitespace is a part of custom property value
-      if (property.text.startsWith('--')) {
-        value = this._customProperty();
-      } else {
-        this._ws();
-        value = this._expr();
-      }
-
+      const value = property.text.startsWith('--')
+        ? this._customProperty() // whitespace is a part of custom property value
+        : (this._ws(), this._expr());
       // if there's no parts for the value, it's an error
       if (!value || value.length === 0) {
-        this._unexpectedToken(stream.LT(1));
+        stream.throwUnexpected(stream.LT(1));
       }
-
-      const important = this._prio();
-
-      /*
-       * If hacks should be allowed, then only check the root
-       * property. If hacks should not be allowed, treat
-       * _property or *property as invalid properties.
-       */
-      let propertyName = property.toString();
-      if (this.options.starHack && property.hack === '*' ||
-          this.options.underscoreHack && property.hack === '_') {
-        propertyName = property.text;
+      let invalid;
+      if (!this.options.skipValidation) {
+        try {
+          /* If hacks are allowed, then only check the root property.
+             Otherwise treat `_property` or `*property` as invalid */
+          const name =
+            this.options.starHack && property.hack === '*' ||
+            this.options.underscoreHack && property.hack === '_'
+              ? property.text
+              : property.toString();
+          validateProperty(name, value);
+        } catch (ex) {
+          invalid = ex;
+        }
       }
-
-      let invalid = null;
-      try {
-        validateProperty(propertyName, value);
-      } catch (ex) {
-        invalid = ex;
-      }
-
       const event = {
         type: 'property',
+        important: stream.match(Tokens.IMPORTANT),
         property,
         value,
-        important,
       };
+      this._ws();
       if (invalid) {
         event.invalid = invalid;
         event.message = invalid.message;
       }
       this.fire(event, property);
-
-      if (consumeSemicolon) stream.match(Tokens.SEMICOLON);
-      return true;
-    }
-
-    _prio() {
-      const result = this._tokenStream.match(Tokens.IMPORTANT_SYM);
+      if (consumeSemicolon) {
+        while (stream.match(TT.semiS)) {/*NOP*/}
+      }
       this._ws();
-      return result;
+      return true;
     }
 
     _expr(inFunction, endToken = Tokens.RPAREN) {
       const stream = this._tokenStream;
       const values = [];
-
       while (true) {
         let value = this._term(inFunction);
-        if (!value && !values.length) return null;
-
+        if (!value && !values.length) {
+          return null;
+        }
         // get everything inside the parens and let validateProperty handle that
         if (!value && inFunction && stream.peek() !== endToken) {
           stream.get();
@@ -4933,64 +4156,52 @@ self.parserlib = (() => {
         } else if (!value) {
           break;
         }
-
         // TODO: remove this hack
         const last = values[values.length - 1];
         if (last && last.offset === value.offset && last.text === value.text) {
           break;
         }
-
         values.push(value);
         this._ws();
-
-        const operator = this._operator(inFunction);
-        if (operator) values.push(operator);
+        const operator = this._tokenStream.match(inFunction ? TT.opInFunc : TT.op);
+        if (operator) {
+          this._ws();
+          values.push(new PropertyValuePart(operator));
+        }
       }
-
       return values[0] ? new PropertyValue(values, values[0]) : null;
     }
 
     _customProperty() {
-      const reader = this._tokenStream._reader;
+      const stream = this._tokenStream;
+      const reader = stream._reader;
       const value = [];
-
-      // a custom property value may end before these characters
-      // that belong to the parent declaration, not to the custom property
-      let end = /[;!})]/;
+      // These chars belong to the parent if used at the top nesting level of the property's value
+      const UNGET = ';!})';
+      let end = UNGET;
       const endings = [];
-
       readValue:
       while (!reader.eof()) {
         const chunk = reader.readMatch(/([^;!'"{}()[\]/]|\/(?!\*))+/y);
         if (chunk) {
           value.push(chunk);
         }
-
         reader.mark();
         const c = reader.read();
         value.push(c);
-
         switch (c) {
           case '/':
-            value.push(reader.readMatch(/([^*]|\*(?!\/))*(\*\/|$)/y));
+            value[value.length - 1] = stream.readComment(c);
             continue;
           case '"':
           case "'":
-            reader.reset();
-            value.pop();
-            value.push(this._tokenStream.readString());
+            value[value.length - 1] = stream.readString(c);
             continue;
           case '{':
-            endings.push(end);
-            end = '}';
-            continue;
           case '(':
-            endings.push(end);
-            end = ')';
-            continue;
           case '[':
             endings.push(end);
-            end = ']';
+            end = c === '{' ? '}' : c === '(' ? ')' : ']';
             continue;
           case ';':
           case '!':
@@ -5002,7 +4213,7 @@ self.parserlib = (() => {
           case '}':
           case ')':
           case ']':
-            if (end instanceof RegExp ? !end.test(c) : c !== end) {
+            if (!end.includes(c)) {
               reader.reset();
               return null;
             }
@@ -5010,8 +4221,7 @@ self.parserlib = (() => {
             if (end) {
               continue;
             }
-            if (c === '}' || c === ')') {
-              // unget parent }
+            if (UNGET.includes(c)) {
               reader.reset();
               value.pop();
             }
@@ -5019,8 +4229,8 @@ self.parserlib = (() => {
         }
       }
       if (!value[0]) return null;
-      const token = this._tokenStream._token;
-      token.value = value.join('');
+      const token = stream._token;
+      token.value = fastJoin(value);
       token.type = Tokens.CUSTOM_PROP;
       return new PropertyValue([new PropertyValuePart(token)], token);
     }
@@ -5028,26 +4238,22 @@ self.parserlib = (() => {
     _term(inFunction) {
       const stream = this._tokenStream;
       const unary = stream.match(TT.plusMinus) && stream._token;
-
       const finalize = (token, value) => {
         if (!token && unary) stream.unget();
         if (!token) return null;
         if (token instanceof SyntaxUnit) return token;
         if (unary) {
-          token.startLine = unary.startLine;
-          token.startCol = unary.startCol;
+          token.line = unary.line;
+          token.col = unary.col;
           token.value = unary.value + (value || token.value);
         } else if (value) {
           token.value = value;
         }
         return new PropertyValuePart(token);
       };
-
-      // exception for IE filters
-      if (stream.peek() === Tokens.IE_FUNCTION && this.options.ieFilters) {
+      if (this.options.ieFilters && stream.peek() === Tokens.IE_FUNCTION) {
         return finalize(this._ieFunction());
       }
-
       // see if it's a simple block
       if (stream.match(inFunction ? TT.LParenBracketBrace : TT.LParenBracket)) {
         const token = stream._token;
@@ -5066,49 +4272,41 @@ self.parserlib = (() => {
     _function({asText} = {}) {
       const stream = this._tokenStream;
       if (!stream.match(Tokens.FUNCTION)) return null;
-
       const start = stream._token;
       const name = start.value.slice(0, -1);
-
       this._ws();
-
       const expr = this._expr(lower(name));
       const ieFilter = this.options.ieFilters && stream.peek() === Tokens.EQUALS ?
         this._functionIeFilter() : '';
       const text = name + '(' + (expr || '') + ieFilter + ')';
-
       stream.mustMatch(Tokens.RPAREN);
       this._ws();
-
-      if (asText) return text;
-
-      const unit = new SyntaxUnit(text, start, 'function');
-      unit.expr = expr;
-      unit.name = name;
-      unit.tokenType = Tokens.FUNCTION;
-      return unit;
+      if (asText) {
+        return text;
+      }
+      return SyntaxUnit.addFuncInfo(
+        new SyntaxUnit(text, start, 'function', {
+          expr,
+          name,
+          tokenType: Tokens.FUNCTION,
+        }));
     }
 
     _functionIeFilter() {
       const stream = this._tokenStream;
       const text = [];
-
       do {
         if (this._ws()) {
           text.push(stream._token.value);
         }
-
         // might be second time in the loop
         if (stream.LA(0) === Tokens.COMMA) {
           text.push(stream._token.value);
         }
-
         stream.match(Tokens.IDENT);
         text.push(stream._token.value);
-
         stream.match(Tokens.EQUALS);
         text.push(stream._token.value);
-
         let lt = stream.peek();
         while (lt !== Tokens.COMMA &&
                lt !== Tokens.S &&
@@ -5119,36 +4317,28 @@ self.parserlib = (() => {
           lt = stream.peek();
         }
       } while (stream.match([Tokens.COMMA, Tokens.S]));
-
-      return text.join('');
+      return fastJoin(text);
     }
 
     _ieFunction() {
       const stream = this._tokenStream;
       let functionText = null;
       let lt;
-
       // IE function can begin like a regular function, too
       if (stream.match([Tokens.IE_FUNCTION, Tokens.FUNCTION])) {
         functionText = stream._token.value;
-
         do {
-
           if (this._ws()) {
             functionText += stream._token.value;
           }
-
           // might be second time in the loop
           if (stream.LA(0) === Tokens.COMMA) {
             functionText += stream._token.value;
           }
-
           stream.match(Tokens.IDENT);
           functionText += stream._token.value;
-
           stream.match(Tokens.EQUALS);
           functionText += stream._token.value;
-
           // functionText += this._term();
           lt = stream.peek();
           while (lt !== Tokens.COMMA && lt !== Tokens.S && lt !== Tokens.RPAREN) {
@@ -5157,55 +4347,34 @@ self.parserlib = (() => {
             lt = stream.peek();
           }
         } while (stream.match([Tokens.COMMA, Tokens.S]));
-
         stream.match(Tokens.RPAREN);
         functionText += ')';
         this._ws();
       }
-
       return functionText;
     }
 
     _hexcolor() {
       const stream = this._tokenStream;
-
       if (!stream.match(Tokens.HASH)) return null;
-
       const token = stream._token;
       const color = token.value;
       const len = color.length;
-
       if (len !== 4 && len !== 5 && len !== 7 && len !== 9 ||
           !/^#([a-f\d]{3}(?:[a-f\d](?:[a-f\d]{2}){0,2})?)$/i.test(color)) {
-        const {startLine, startCol} = token;
-        throw new SyntaxError(
-          `Expected a hex color but found '${color}' at line ${startLine}, col ${startCol}.`,
-          {startLine, startCol});
+        throw new SyntaxError(`Expected a hex color but found '${color}'.`, token);
       }
-
       this._ws();
       return token;
     }
 
-    //-----------------------------------------------------------------
-    // Animations methods
-    //-----------------------------------------------------------------
-
-    _keyframes() {
+    _keyframes(start) {
       const stream = this._tokenStream;
-      const token = stream.mustMatch(Tokens.KEYFRAMES_SYM);
-      const prefix = /^@-([^-]+)-/.test(token.value) ? RegExp.$1 : '';
-
+      const prefix = /^@-([^-]+)-/.test(start.value) ? RegExp.$1 : '';
       this._ws();
       const name = this._keyframeName();
-
       stream.mustMatch(Tokens.LBRACE);
-      this.fire({
-        type: 'startkeyframes',
-        name,
-        prefix,
-      }, token);
-
+      this.fire({type: 'startkeyframes', name, prefix}, start);
       // check for key
       while (true) {
         this._ws();
@@ -5213,13 +4382,8 @@ self.parserlib = (() => {
         if (tt !== Tokens.IDENT && tt !== Tokens.PERCENTAGE) break;
         this._keyframeRule();
       }
-
       stream.mustMatch(Tokens.RBRACE);
-      this.fire({
-        type: 'endkeyframes',
-        name,
-        prefix,
-      });
+      this.fire({type: 'endkeyframes', name, prefix});
       this._ws();
     }
 
@@ -5230,63 +4394,41 @@ self.parserlib = (() => {
     }
 
     _keyframeRule() {
-      const keyList = this._keyList();
-
-      this.fire({
-        type: 'startkeyframerule',
-        keys: keyList,
-      }, keyList[0]);
-
+      const keys = this._keyList();
+      this.fire({type: 'startkeyframerule', keys}, keys[0]);
       this._readDeclarations();
-
-      this.fire({
-        type: 'endkeyframerule',
-        keys: keyList,
-      });
+      this.fire({type: 'endkeyframerule', keys});
     }
 
     _keyList() {
       const stream = this._tokenStream;
       const keyList = [];
-
       // must be least one key
       keyList.push(this._key());
-
       this._ws();
-
       while (stream.match(Tokens.COMMA)) {
         this._ws();
         keyList.push(this._key());
         this._ws();
       }
-
       return keyList;
     }
 
     _key() {
       const stream = this._tokenStream;
-      let token;
-
       if (stream.match(Tokens.PERCENTAGE)) {
         return SyntaxUnit.fromToken(stream._token);
-      } else if (stream.match(Tokens.IDENT)) {
-        token = stream._token;
-
-        if (/from|to/i.test(token.value)) {
-          return SyntaxUnit.fromToken(token);
+      }
+      if (stream.match(Tokens.IDENT)) {
+        if (/^(from|to)$/i.test(stream._token.value)) {
+          return SyntaxUnit.fromToken(stream._token);
         }
-
         stream.unget();
       }
-
       // if it gets here, there wasn't a valid token, so time to explode
-      this._unexpectedToken(stream.LT(1));
+      stream.throwUnexpected(stream.LT(1), ['%', "'from'", "'to'"]);
     }
 
-    //-----------------------------------------------------------------
-    // Helper methods
-    //-----------------------------------------------------------------
-
     _skipCruft() {
       while (this._tokenStream.match(TT.cruft)) { /*NOP*/ }
     }
@@ -5304,74 +4446,92 @@ self.parserlib = (() => {
     } = {}) {
       const stream = this._tokenStream;
       if (checkStart) stream.mustMatch(Tokens.LBRACE);
-
-      try {
-        while (stream.peek() !== Tokens.RBRACE) {
-          this._ws(true);
-          if (stream.match(Tokens.SEMICOLON) || readMargins && this._margin()) continue;
-          if (!this._declaration(true)) break;
-        }
-        stream.mustMatch(Tokens.RBRACE);
-        if (!stopAfterBrace) this._ws();
-        return;
-
-      } catch (ex) {
-        // if not a syntax error, rethrow it
-        if (!(ex instanceof SyntaxError) || this.options.strict) throw ex;
-
-        this.fire(Object.assign({}, ex, {type: 'error', error: ex}));
-
-        switch (stream.advance([Tokens.SEMICOLON, Tokens.RBRACE])) {
-          case Tokens.SEMICOLON:
-            // see if there's another declaration
-            this._readDeclarations({checkStart: false, readMargins, stopAfterBrace});
-            return;
-          case Tokens.RBRACE:
-            // the rule is finished
-            return;
-          default:
-            // rethrow the error because it wasn't handled properly
-            throw ex;
+      for (let next, tt; (tt = (next = stream.get(true)).type) !== Tokens.RBRACE;) {
+        try {
+          // Pre-check to avoid calling _ws too much as it's wasteful
+          if (tt === Tokens.S ||
+              tt === Tokens.COMMENT ||
+              tt === Tokens.USO_VAR) {
+            this._ws(next, true);
+            tt = 0;
+          }
+          if (tt === Tokens.SEMICOLON ||
+              readMargins && this._margin() ||
+              (tt && stream.unget(), this._declaration(true)) ||
+              (next = stream.LT(1)).type === Tokens.SEMICOLON) {
+            continue;
+          }
+          stream.mustMatch(Tokens.RBRACE);
+          if (!stopAfterBrace) this._ws();
+          break;
+        } catch (ex) {
+          this._readDeclarationsRecovery(ex, arguments[0]);
         }
       }
     }
 
-    _ws(skipUsoVar) {
-      let ws = '';
+    _readDeclarationsRecovery(ex) {
+      if (ex) {
+        if (this.options.strict || !(ex instanceof SyntaxError)) {
+          throw ex; // if not a syntax error, rethrow it
+        }
+        this.fire(Object.assign({}, ex, {
+          type: ex.type || 'error',
+          recoverable: true,
+          error: ex,
+        }));
+      }
+      switch (this._tokenStream.advance([Tokens.SEMICOLON, Tokens.RBRACE])) {
+        case Tokens.SEMICOLON:
+          return true; // continue to the next declaration
+        case Tokens.RBRACE:
+          this._tokenStream.unget();
+          return;
+        default:
+          throw ex;
+      }
+    }
+
+    _ws(start, skipUsoVar) {
       const stream = this._tokenStream;
       const tokens = skipUsoVar ? TT.usoS : Tokens.S;
+      let ws = start ? start.value : '';
+      for (let t; (t = stream.LT(1, true)) && t.type === Tokens.S;) {
+        ws += stream.get(true).value;
+      }
+      if (stream._ltIndex === stream._ltAhead) {
+        ws += stream.readWhitespace();
+        if (!stream._reader.peekTest(/\/\*/y)) {
+          return ws;
+        }
+      }
       while (stream.match(tokens)) {
         ws += stream._token.value;
       }
       return ws;
     }
 
-    _unknownSym() {
+    _unknownSym(start) {
       const stream = this._tokenStream;
-      stream.get();
-      const lt0 = stream.LT(0);
       if (this.options.strict) {
-        throw new SyntaxError('Unknown @ rule.', lt0);
+        throw new SyntaxError('Unknown @ rule.', start);
       }
-
       this._ws();
       const simpleValue =
         stream.match(TT.identCustom) && SyntaxUnit.fromToken(stream._token) ||
         stream.peek() === Tokens.FUNCTION && this._function({asText: true}) ||
         this._unknownBlock(TT.LParenBracket);
-
       this._ws();
       const blockValue = this._unknownBlock();
       if (!blockValue) {
         stream.match(Tokens.SEMICOLON);
       }
-
       this.fire({
         type: 'unknown-at-rule',
-        name: lt0.value,
+        name: start.value,
         simpleValue,
         blockValue,
-      }, lt0);
+      }, start);
       this._ws();
     }
 
@@ -5385,8 +4545,8 @@ self.parserlib = (() => {
       const reader = stream._reader;
       reader.mark();
       reader._cursor = start.offset;
-      reader._line = start.startLine;
-      reader._col = start.startCol;
+      reader._line = start.line;
+      reader._col = start.col;
       const value = [];
       const endings = [];
       let blockEnd;
@@ -5404,7 +4564,7 @@ self.parserlib = (() => {
           blockEnd = endings.pop();
           if (!blockEnd) {
             stream.resetLT();
-            return new SyntaxUnit(value.join(''), start);
+            return new SyntaxUnit(fastJoin(value), start);
           }
         }
       }
@@ -5412,21 +4572,13 @@ self.parserlib = (() => {
       return null;
     }
 
-    _unexpectedToken(token = this._tokenStream._token) {
-      const {value, startLine: line, startCol: col} = token;
-      throw new SyntaxError(`Unexpected token '${value}' at line ${line}, col ${col}.`, token);
-    }
-
     _verifyEnd() {
-      if (this._tokenStream.LA(1) !== Tokens.EOF) {
-        this._unexpectedToken(this._tokenStream.LT(1));
+      const stream = this._tokenStream;
+      if (stream.peek() !== Tokens.EOF) {
+        stream.throwUnexpected(stream.LT(1));
       }
     }
 
-    //-----------------------------------------------------------------
-    // Parsing methods
-    //-----------------------------------------------------------------
-
     parse(input, {reuseCache} = {}) {
       this._tokenStream = new TokenStream(input);
       parserCache.start(reuseCache && this);
@@ -5580,42 +4732,23 @@ self.parserlib = (() => {
     ]),
   };
 
-  //endregion
-  //region Helper functions
+  //#endregion
+  //#region Helper functions
 
-  function isHexDigit(c) {
-    return (
-      c >= '0' && c <= '9' ||
-      c >= 'a' && c <= 'f' ||
-      c >= 'A' && c <= 'F');
+  function escapeChar(c) {
+    return c === '"' ? '\\' + c : `\\${c.codePointAt(0).toString(16)} `;
   }
 
-  function isDigit(c) {
-    return c >= '0' && c <= '9';
+  function fastJoin(arr) {
+    return !arr.length ? '' :
+      arr.length === 1 ? `${arr[0]}` :
+        arr.length === 2 ? `${arr[0]}${arr[1]}` :
+          arr.join('');
   }
 
-  function isWhitespace(c) {
-    return (c === ' ' || c === '\t' || c === '\n' || c === '\f' || c === '\r');
-  }
-
-  function isNewLine(c) {
-    return (c === '\n' || c === '\r\n' || c === '\r' || c === '\f');
-  }
-
-  function isNameStart(c) {
-    return (
-      c >= 'a' && c <= 'z' ||
-      c >= 'A' && c <= 'Z' ||
-      c === '_' || c === '\\' ||
-      c >= '\u00A0' && c <= '\uFFFF');
-  }
-
-  function isNameChar(c) {
-    return (c === '-' || c >= '0' && c <= '9' || isNameStart(c));
-  }
-
-  function isIdentStart(c) {
-    return c === '-' || isNameStart(c);
+  /** @param {PropertyValuePart} p */
+  function hasUsoVarPart(p) {
+    return p.tokenType === Tokens.USO_VAR;
   }
 
   function isPseudoElement(pseudo) {
@@ -5623,29 +4756,48 @@ self.parserlib = (() => {
            /^:(first-(letter|line)|before|after)$/i.test(pseudo);
   }
 
+  function lower(text) {
+    if (typeof text !== 'string') text = `${text}`;
+    let result = lowercaseCache.get(text);
+    if (result) return result;
+    result = text.toLowerCase();
+    lowercaseCache.set(text, result);
+    return result;
+  }
+
+  function lowerCmp(a, b) {
+    return a.length === b.length && (a === b || lower(a) === lower(b));
+  }
+
+  /** @this {String} */
+  function lowerCmpThis(a) {
+    return a.length === this.length && (a === this || lower(a) === lower(this));
+  }
+
   function parseString(str) {
-    const replacer = (match, esc) => {
-      if (isNewLine(esc)) return '';
-      const m = /^[0-9a-f]{1,6}/i.exec(esc);
-      return m ? String.fromCodePoint(parseInt(m[0], 16)) : esc;
-    };
-    // Strip surrounding single/double quotes
-    str = str.slice(1, -1);
-    return str.replace(/\\(\r\n|[^\r0-9a-f]|[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?)/ig, replacer);
+    return str.slice(1, -1) // strip surrounding quotes
+      .replace(/\\(\r\n|[^\r0-9a-f]|[0-9a-f]{1,6}(\r\n|[ \n\r\t\f])?)/ig, unescapeChar);
   }
 
   function serializeString(value) {
-    const replacer = c => {
-      if (c === '"') return '\\' + c;
-      // We only escape non-surrogate chars, so using charCodeAt is harmless here.
-      const cp = String.codePointAt ? c.codePointAt(0) : c.charCodeAt(0);
-      return '\\' + cp.toString(16) + ' ';
-    };
-    return '"' + value.replace(/["\r\n\f]/g, replacer) + '"';
+    return `"${value.replace(/["\r\n\f]/g, escapeChar)}"`;
   }
 
-  //endregion
-  //region PUBLIC API
+  function stickyTest(rx, i, text) {
+    rx.lastIndex = i;
+    return rx.test(text);
+  }
+
+  function unescapeChar(m, c) {
+    if (c === '\n' || c === '\r\n' || c === '\r' || c === '\f') {
+      return '';
+    }
+    m = /^[0-9a-f]{1,6}/i.exec(c);
+    return m ? String.fromCodePoint(parseInt(m[0], 16)) : c;
+  }
+
+  //#endregion
+  //#region PUBLIC API
 
   return {
     css: {
@@ -5676,7 +4828,5 @@ self.parserlib = (() => {
     cache: parserCache,
   };
 
-  //endregion
+  //#endregion
 })();
-
-self.parserlib.css.Tokens[self.parserlib.css.Tokens.COMMENT].hide = false;