diff --git a/background/storage.js b/background/storage.js
index af65afd4..de4f8a0c 100644
--- a/background/storage.js
+++ b/background/storage.js
@@ -370,7 +370,7 @@ function filterStylesInternal({
 
 
 // Parse the source and find the duplication
-// {id: int, style: object, source: string, checkDup: boolean}
+// {id: int, style: object, sourceCode: string, checkDup: boolean}
 function filterUsercss(req) {
   let style;
   let pendingBuild;
@@ -381,8 +381,8 @@ function filterUsercss(req) {
 
   function buildMeta() {
     return new Promise(resolve => {
-      if (req.source) {
-        style = usercss.buildMeta(req.source);
+      if (req.sourceCode) {
+        style = usercss.buildMeta(req.sourceCode);
       } else {
         style = req.style;
       }
@@ -426,8 +426,8 @@ function saveUsercss(style) {
 
   function buildMeta() {
     return new Promise(resolve => {
-      if (!style.name || !style.namespace) {
-        resolve(Object.assign(usercss.buildMeta(style.source), style));
+      if (!style.usercssData) {
+        resolve(Object.assign(usercss.buildMeta(style.sourceCode), style));
         return;
       }
       resolve(style);
@@ -449,26 +449,32 @@ function saveStyle(style) {
   let existed;
   let codeIsUpdated;
 
-  if (style.usercss) {
-    return processUsercss(style).then(decide);
-  }
+  const maybeProcess = style.usercssData ? processUsercss() : Promise.resolve();
 
-  if (reason === 'update' || reason === 'update-digest') {
-    return calcStyleDigest(style).then(digest => {
-      style.originalDigest = digest;
-      return decide();
-    });
-  }
-  if (reason === 'import') {
-    style.originalDigest = style.originalDigest || style.styleDigest; // TODO: remove in the future
-    delete style.styleDigest; // TODO: remove in the future
-    if (typeof style.originalDigest !== 'string' || style.originalDigest.length !== 40) {
-      delete style.originalDigest;
+  return maybeProcess
+    .then(maybeUpdate)
+    .then(maybeImportFix)
+    .then(decide);
+
+  function maybeUpdate() {
+    if (reason === 'update' || reason === 'update-digest') {
+      return calcStyleDigest(style).then(digest => {
+        style.originalDigest = digest;
+      });
     }
   }
-  return decide();
 
-  function processUsercss(style) {
+  function maybeImportFix() {
+    if (reason === 'import') {
+      style.originalDigest = style.originalDigest || style.styleDigest; // TODO: remove in the future
+      delete style.styleDigest; // TODO: remove in the future
+      if (typeof style.originalDigest !== 'string' || style.originalDigest.length !== 40) {
+        delete style.originalDigest;
+      }
+    }
+  }
+
+  function processUsercss() {
     return findDupUsercss(style)
       .then(dup => {
         if (!dup) {
@@ -477,11 +483,10 @@ function saveStyle(style) {
         if (!id) {
           id = dup.id;
         }
-        if (reason === 'config') {
-          return;
+        if (reason !== 'config') {
+          // preserve style.vars during update
+          usercss.assignVars(style, dup);
         }
-        // preserve style.vars during update
-        usercss.assignVars(style, dup);
       })
       .then(() => usercss.buildCode(style));
   }
@@ -538,7 +543,7 @@ function saveStyle(style) {
         style, codeIsUpdated, reason,
       });
     }
-    if (style.usercss && !existed && reason === 'install') {
+    if (style.usercssData && !existed && reason === 'update') {
       // open the editor for usercss with the first install?
       openEditor(style.id);
     }
@@ -563,7 +568,13 @@ function findDupUsercss(style) {
     return getStyles({id: style.id}).then(s => s[0]);
   }
   return getStyles().then(styles =>
-    styles.find(s => s.name === style.name && s.namespace === style.namespace)
+    styles.find(target => {
+      if (!target.usercssData) {
+        return false;
+      }
+      return target.usercssData.name === style.usercssData.name &&
+        target.usercssData.namespace === style.usercssData.namespace;
+    })
   );
 }
 
@@ -815,7 +826,8 @@ function normalizeStyleSections({sections}) {
 
 
 function calcStyleDigest(style) {
-  const jsonString = JSON.stringify(normalizeStyleSections(style));
+  const jsonString = style.usercssData ?
+    style.sourceCode : JSON.stringify(normalizeStyleSections(style));
   const text = new TextEncoder('utf-8').encode(jsonString);
   return crypto.subtle.digest('SHA-1', text).then(hex);
 
diff --git a/background/update.js b/background/update.js
index 32ef9b1a..db1c5fd3 100644
--- a/background/update.js
+++ b/background/update.js
@@ -64,7 +64,7 @@ var updater = {
 
     'ignoreDigest' option is set on the second manual individual update check on the manage page.
     */
-    const maybeUpdate = style.usercss ? maybeUpdateUsercss : maybeUpdateUSO;
+    const maybeUpdate = style.usercssData ? maybeUpdateUsercss : maybeUpdateUSO;
     return (ignoreDigest ? Promise.resolve() : calcStyleDigest(style))
       .then(checkIfEdited)
       .then(maybeUpdate)
@@ -83,9 +83,7 @@ var updater = {
       if (ignoreDigest) {
         return;
       }
-      if (style.usercss && style.edited) {
-        return Promise.reject(updater.EDITED);
-      } else if (style.originalDigest && style.originalDigest !== digest) {
+      if (style.originalDigest && style.originalDigest !== digest) {
         return Promise.reject(updater.EDITED);
       }
     }
@@ -106,12 +104,14 @@ var updater = {
     function maybeUpdateUsercss() {
       return download(style.updateUrl).then(text => {
         const json = usercss.buildMeta(text);
+        const {usercssData: {version}} = style;
+        const {usercssData: {version: newVersion}} = json;
         // re-install is invalid in a soft upgrade
-        if (semverCompare(style.version, json.version) === 0 && !ignoreDigest) {
+        if (semverCompare(version, newVersion) === 0 && !ignoreDigest) {
           return Promise.reject(updater.SAME_VERSION);
         }
         // downgrade is always invalid
-        if (semverCompare(style.version, json.version) > 0) {
+        if (semverCompare(version, newVersion) > 0) {
           return Promise.reject(updater.ERROR_VERSION);
         }
         return json;
@@ -121,7 +121,7 @@ var updater = {
     function maybeSave(json) {
       json.id = style.id;
       // no need to compare section code for usercss, they are built dynamically
-      if (!json.usercss) {
+      if (!json.usercssData) {
         if (!styleJSONseemsValid(json)) {
           return Promise.reject(updater.ERROR_JSON);
         }
diff --git a/content/install-user-css.js b/content/install-user-css.js
index b084784a..4dc073ed 100644
--- a/content/install-user-css.js
+++ b/content/install-user-css.js
@@ -7,7 +7,7 @@ let pendingResource;
 function install(style) {
   const request = Object.assign(style, {
     method: 'saveUsercss',
-    reason: 'install',
+    reason: 'update',
     updateUrl: location.href
   });
   return runtimeSend(request)
@@ -55,7 +55,9 @@ function getAppliesTo(style) {
 
 function initInstallPage({style, dup}, sourceLoader) {
   return pendingResource.then(() => {
-    const versionTest = dup && semverCompare(style.version, dup.version);
+    const data = style.usercssData;
+    const dupData = dup && dup.usercssData;
+    const versionTest = dup && semverCompare(data.version, dupData.version);
     document.body.textContent = '';
     document.body.appendChild(buildPage());
 
@@ -65,13 +67,15 @@ function initInstallPage({style, dup}, sourceLoader) {
         $('.actions')
       );
     }
-    $('.code').textContent = style.source;
+    $('.code').textContent = style.sourceCode;
     $('button.install').onclick = () => {
       if (dup) {
-        if (confirm(chrome.i18n.getMessage('styleInstallOverwrite', [style.name, dup.version, style.version]))) {
+        if (confirm(chrome.i18n.getMessage('styleInstallOverwrite', [
+          data.name, dupData.version, data.version
+        ]))) {
           install(style);
         }
-      } else if (confirm(chrome.i18n.getMessage('styleInstall', [style.name]))) {
+      } else if (confirm(chrome.i18n.getMessage('styleInstall', [data.name]))) {
         install(style);
       }
     };
@@ -87,19 +91,19 @@ function initInstallPage({style, dup}, sourceLoader) {
             $element({tag: 'button', className: 'install', textContent: installButtonLabel()})
           ]}),
           $element({tag: 'h1', appendChild: [
-            style.name,
-            $element({tag: 'small', className: 'meta-version', textContent: style.version})
+            data.name,
+            $element({tag: 'small', className: 'meta-version', textContent: data.version})
           ]}),
-          $element({tag: 'p', textContent: style.description}),
-          style.author && $element({tag: 'h3', textContent: t('author')}),
-          style.author,
-          style.license && $element({tag: 'h3', textContent: t('license')}),
-          style.license,
+          $element({tag: 'p', textContent: data.description}),
+          data.author && $element({tag: 'h3', textContent: t('author')}),
+          data.author,
+          data.license && $element({tag: 'h3', textContent: t('license')}),
+          data.license,
           $element({tag: 'h3', textContent: t('appliesLabel')}),
           $element({tag: 'ul', appendChild: getAppliesTo(style).map(
             pattern => $element({tag: 'li', textContent: pattern})
           )}),
-          externalLink(style),
+          externalLink(),
         ]}),
         $element({className: 'main', appendChild: [
           $element({className: 'code'})
@@ -107,13 +111,13 @@ function initInstallPage({style, dup}, sourceLoader) {
       ]});
     }
 
-    function externalLink(style) {
+    function externalLink() {
       const urls = [];
-      if (style.url) {
-        urls.push([style.url, t('externalHomepage')]);
+      if (data.homepageURL) {
+        urls.push([data.homepageURL, t('externalHomepage')]);
       }
-      if (style.supportURL) {
-        urls.push([style.supportURL, t('externalSupport')]);
+      if (data.supportURL) {
+        urls.push([data.supportURL, t('externalSupport')]);
       }
       if (urls.length) {
         return $element({appendChild: [
@@ -139,7 +143,7 @@ function initLiveReload(sourceLoader) {
     return runtimeSend({
       method: 'saveUsercss',
       id: installed.id,
-      source: source
+      sourceCode: source
     }).then(() => {
       $$('.main .warning').forEach(e => e.remove());
     }).catch(err => {
@@ -267,7 +271,7 @@ function initUsercssInstall() {
     .then(() =>
       runtimeSend({
         method: 'filterUsercss',
-        source: sourceLoader.source(),
+        sourceCode: sourceLoader.source(),
         checkDup: true
       })
     )
diff --git a/edit/edit.js b/edit/edit.js
index 0187abdc..256ddd7e 100644
--- a/edit/edit.js
+++ b/edit/edit.js
@@ -1352,7 +1352,7 @@ function setStyleMeta(style) {
 
 function initWithStyle(request) {
   if (!editor) {
-    if (!request.style.usercss) {
+    if (!request.style.usercssData) {
       initWithSectionStyle(request);
     } else {
       editor = createSourceEditor(request.style);
diff --git a/edit/source-editor.js b/edit/source-editor.js
index 3469e98e..1a9ee4a3 100644
--- a/edit/source-editor.js
+++ b/edit/source-editor.js
@@ -26,7 +26,7 @@ function createSourceEditor(style) {
   );
 
   // draw CodeMirror
-  $('#sections textarea').value = style.source;
+  $('#sections textarea').value = style.sourceCode;
   const cm = CodeMirror.fromTextArea($('#sections textarea'));
   // too many functions depend on this global
   editors.push(cm);
@@ -378,8 +378,8 @@ function createSourceEditor(style) {
     // source
     cm.on('change', () => {
       const value = cm.getValue();
-      dirty.modify('source', style.source, value);
-      style.source = value;
+      dirty.modify('source', style.sourceCode, value);
+      style.sourceCode = value;
 
       updateLintReportIfEnabled(cm);
     });
@@ -402,10 +402,11 @@ function createSourceEditor(style) {
     $('#name').value = style.name;
     $('#enabled').checked = style.enabled;
     $('#url').href = style.url;
-    cm.setOption('mode', MODE[style.preprocessor] || 'css');
-    CodeMirror.autoLoadMode(cm, style.preprocessor || 'css');
+    const {usercssData: {preprocessor}} = style;
+    cm.setOption('mode', MODE[preprocessor] || 'css');
+    CodeMirror.autoLoadMode(cm, MODE[preprocessor] || 'css');
     // beautify only works with regular CSS
-    $('#beautify').disabled = Boolean(style.preprocessor);
+    $('#beautify').disabled = MODE[preprocessor] && MODE[preprocessor] !== 'css';
     updateTitle();
   }
 
@@ -417,9 +418,9 @@ function createSourceEditor(style) {
   function replaceStyle(newStyle) {
     style = deepCopy(newStyle);
     updateMetas();
-    if (style.source !== cm.getValue()) {
+    if (style.sourceCode !== cm.getValue()) {
       const cursor = cm.getCursor();
-      cm.setValue(style.source);
+      cm.setValue(style.sourceCode);
       cm.setCursor(cursor);
     }
     dirty.clear();
@@ -448,8 +449,7 @@ function createSourceEditor(style) {
       reason: 'editSave',
       id: style.id,
       enabled: style.enabled,
-      edited: dirty.has('source'),
-      source: style.source
+      sourceCode: style.sourceCode
     };
     return onBackgroundReady().then(() => BG.saveUsercss(req))
       .then(result => {
diff --git a/js/usercss.js b/js/usercss.js
index 2841efd5..e0d1745f 100644
--- a/js/usercss.js
+++ b/js/usercss.js
@@ -4,10 +4,23 @@
 
 // eslint-disable-next-line no-var
 var usercss = (function () {
-  const METAS = [
-    'author', 'advanced', 'description', 'homepageURL', 'icon', 'license', 'name',
-    'namespace', 'noframes', 'preprocessor', 'supportURL', 'var', 'version'
-  ];
+  // true for global, false for private
+  const METAS = {
+    __proto__: null,
+    author: true,
+    advanced: false,
+    description: true,
+    homepageURL: false,
+    // icon: false,
+    license: false,
+    name: true,
+    namespace: false,
+    // noframes: false,
+    preprocessor: false,
+    supportURL: false,
+    'var': false,
+    version: false
+  };
 
   const META_VARS = ['text', 'color', 'checkbox', 'select', 'dropdown', 'image'];
 
@@ -222,7 +235,7 @@ var usercss = (function () {
       parseStringToEnd(state);
       result.default = state.value;
     }
-    state.style.vars[result.name] = result;
+    state.usercssData.vars[result.name] = result;
   }
 
   function parseEOT(state) {
@@ -319,72 +332,71 @@ var usercss = (function () {
     return s;
   }
 
-  function _buildMeta(source) {
-    const style = {
-      name: null,
-      usercss: true,
-      version: null,
-      source: source,
-      edited: false,
-      enabled: true,
-      sections: [],
-      vars: {},
-      preprocessor: null,
-      noframes: false
+  function _buildMeta(sourceCode) {
+    const usercssData = {
+      vars: {}
     };
 
-    const text = getMetaSource(source);
+    const style = {
+      enabled: true,
+      sourceCode,
+      sections: [],
+      usercssData
+    };
+
+    const text = getMetaSource(sourceCode);
     const re = /@(\w+)\s+/mg;
-    const state = {style, re, text};
+    const state = {style, re, text, usercssData};
 
     let match;
     while ((match = re.exec(text))) {
       state.key = match[1];
-      if (!METAS.includes(state.key)) {
+      if (!(state.key in METAS)) {
         continue;
       }
-      if (state.key === 'noframes') {
-        style.noframes = true;
-      } else if (state.key === 'var' || state.key === 'advanced') {
+      if (state.key === 'var' || state.key === 'advanced') {
         if (state.key === 'advanced') {
           state.maybeUSO = true;
         }
         parseVar(state);
       } else {
         parseStringToEnd(state);
-        if (state.key === 'homepageURL') {
-          style.url = state.value;
-        } else {
-          style[state.key] = state.value;
-        }
+        usercssData[state.key] = state.value;
+      }
+      if (METAS[state.key]) {
+        style[state.key] = usercssData[state.key];
       }
     }
-    if (state.maybeUSO && !style.preprocessor) {
-      style.preprocessor = 'uso';
+    if (state.maybeUSO && !usercssData.preprocessor) {
+      usercssData.preprocessor = 'uso';
+    }
+    if (usercssData.homepageURL) {
+      style.url = usercssData.homepageURL;
     }
 
     return style;
   }
 
   function buildCode(style) {
+    const {usercssData: {preprocessor, vars}, sourceCode} = style;
     let builder;
-    if (style.preprocessor) {
-      if (!BUILDER.hasOwnProperty(style.preprocessor)) {
-        return Promise.reject(new Error(`Unsupported preprocessor: ${style.preprocessor}`));
+    if (preprocessor) {
+      if (!BUILDER[preprocessor]) {
+        return Promise.reject(new Error(`Unsupported preprocessor: ${preprocessor}`));
       }
-      builder = BUILDER[style.preprocessor];
+      builder = BUILDER[preprocessor];
     } else {
       builder = BUILDER.default;
     }
 
-    const vars = simpleVars(style.vars);
+    const sVars = simpleVars(vars);
 
     return Promise.resolve().then(() => {
       // preprocess
       if (builder.preprocess) {
-        return builder.preprocess(style.source, vars);
+        return builder.preprocess(sourceCode, sVars);
       }
-      return style.source;
+      return sourceCode;
     }).then(mozStyle =>
       // moz-parser
       loadScript('/js/moz-parser.js').then(() =>
@@ -395,7 +407,7 @@ var usercss = (function () {
     ).then(() => {
       // postprocess
       if (builder.postprocess) {
-        return builder.postprocess(style.sections, vars);
+        return builder.postprocess(style.sections, sVars);
       }
     }).then(() => style);
   }
@@ -414,22 +426,23 @@ var usercss = (function () {
   }
 
   function validate(style) {
+    const {usercssData: data} = style;
     // mandatory fields
     for (const prop of ['name', 'namespace', 'version']) {
-      if (!style[prop]) {
+      if (!data[prop]) {
         throw new Error(chrome.i18n.getMessage('styleMissingMeta', prop));
       }
     }
     // validate version
-    semverCompare(style.version, '0.0.0');
+    semverCompare(data.version, '0.0.0');
 
     // validate URLs
-    validUrl(style.url);
-    validUrl(style.supportURL);
+    validUrl(data.homepageURL);
+    validUrl(data.supportURL);
 
     // validate vars
-    for (const key of Object.keys(style.vars)) {
-      validVar(style.vars[key]);
+    for (const key of Object.keys(data.vars)) {
+      validVar(data.vars[key]);
     }
   }
 
@@ -456,14 +469,16 @@ var usercss = (function () {
   }
 
   function assignVars(style, old) {
+    const {usercssData: {vars}} = style;
+    const {usercssData: {vars: oldVars}} = old;
     // The type of var might be changed during the update. Set value to null if the value is invalid.
-    for (const key of Object.keys(style.vars)) {
-      if (old.vars[key] && old.vars[key].value) {
-        style.vars[key].value = old.vars[key].value;
+    for (const key of Object.keys(vars)) {
+      if (oldVars[key] && oldVars[key].value) {
+        vars[key].value = oldVars[key].value;
         try {
-          validVar(style.vars[key], 'value');
+          validVar(vars[key], 'value');
         } catch (e) {
-          style.vars[key].value = null;
+          vars[key].value = null;
         }
       }
     }
diff --git a/manage/config-dialog.js b/manage/config-dialog.js
index 25d7635e..b802ac4a 100644
--- a/manage/config-dialog.js
+++ b/manage/config-dialog.js
@@ -27,7 +27,7 @@ function configDialog(style) {
 
   function buildConfigForm() {
     const labels = [];
-    const vars = deepCopy(style.vars);
+    const vars = deepCopy(style.usercssData.vars);
     for (const key of Object.keys(vars)) {
       const va = vars[key];
       let appendChild;
diff --git a/manage/manage.js b/manage/manage.js
index 2400a7a9..3200a6e9 100644
--- a/manage/manage.js
+++ b/manage/manage.js
@@ -193,7 +193,7 @@ function createStyleElement({style, name}) {
   if (style.updateUrl && newUI.enabled) {
     $('.actions', entry).appendChild(template.updaterIcons.cloneNode(true));
   }
-  if (style.vars && Object.keys(style.vars).length && newUI.enabled) {
+  if (shouldShowConfig() && newUI.enabled) {
     $('.actions', entry).appendChild(template.configureIcon.cloneNode(true));
   }
 
@@ -202,6 +202,13 @@ function createStyleElement({style, name}) {
   createStyleTargetsElement({entry, style, postponeFavicons: name});
 
   return entry;
+
+  function shouldShowConfig() {
+    if (!style.usercssData) {
+      return false;
+    }
+    return Object.keys(style.usercssData.vars).length > 0;
+  }
 }
 
 
@@ -293,7 +300,7 @@ Object.assign(handleEvent, {
       }
       style.reason = 'config';
       for (const key of keys) {
-        style.vars[key].value = vars[key].value;
+        style.usercssData.vars[key].value = vars[key].value;
       }
       saveStyleSafe(style);
     });