diff --git a/edit/linter-manager.js b/edit/linter-manager.js
index 981dc63c..526048cb 100644
--- a/edit/linter-manager.js
+++ b/edit/linter-manager.js
@@ -131,6 +131,7 @@ linterMan.DEFAULTS = {
     'duplicate-properties': 1,
     'empty-rules': 1,
     'errors': 1,
+    'globals-in-document': 1,
     'known-properties': 1,
     'selector-newline': 1,
     'shorthand-overrides': 1,
diff --git a/js/csslint/csslint.js b/js/csslint/csslint.js
index 8ad8c3a7..43c7df6a 100644
--- a/js/csslint/csslint.js
+++ b/js/csslint/csslint.js
@@ -1003,6 +1003,26 @@ CSSLint.addRule['font-sizes'] = [{
   });
 }];
 
+CSSLint.addRule['globals-in-document'] = [{
+  name: 'Warn about global @ rules inside @-moz-document',
+  desc: 'Warn about @import, @charset, @namespace inside @-moz-document',
+  browsers: 'All',
+}, (rule, parser, reporter) => {
+  let level = 0;
+  let index = 0;
+  parser.addListener('startdocument', () => level++);
+  parser.addListener('enddocument', () => level-- * index++);
+  const check = event => {
+    if (level && index) {
+      reporter.report(`A nested @${event.type} is valid only if this @-moz-document section ` +
+        'is the first one matched for any given URL.', event, rule);
+    }
+  };
+  parser.addListener('import', check);
+  parser.addListener('charset', check);
+  parser.addListener('namespace', check);
+}];
+
 CSSLint.addRule['gradients'] = [{
   name: 'Require all gradient definitions',
   desc: 'When using a vendor-prefixed gradient, make sure to use them all.',
diff --git a/js/csslint/parserlib.js b/js/csslint/parserlib.js
index 7c6375bd..b3c11731 100644
--- a/js/csslint/parserlib.js
+++ b/js/csslint/parserlib.js
@@ -3439,31 +3439,16 @@ self.parserlib = (() => {
     _stylesheet() {
       const stream = this._tokenStream;
       this.fire('startstylesheet');
-      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();
-        }
-      }
+      this._sheetGlobals();
       const {topDocOnly} = this.options;
       const allowedActions = topDocOnly ? Parser.ACTIONS.topDoc : Parser.ACTIONS.stylesheet;
       for (let tt, token; (tt = (token = stream.get(true)).type); this._skipCruft()) {
         try {
-          let action = allowedActions.get(tt);
+          const action = allowedActions.get(tt);
           if (action) {
             action.call(this, token);
             continue;
           }
-          action = Parser.ACTIONS.stylesheetMisplaced.get(tt);
-          if (action) {
-            action.call(this, token, true);
-            throw new SyntaxError(Tokens[tt].text + ' not allowed here.', token);
-          }
           if (topDocOnly) {
             stream.readDeclValue({stopOn: '{}'});
             if (stream._reader.peek() === '{') {
@@ -3489,25 +3474,40 @@ self.parserlib = (() => {
       this.fire('endstylesheet');
     }
 
-    _charset(start, misplaced) {
+    _sheetGlobals() {
+      const stream = this._tokenStream;
+      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();
+        }
+      }
+    }
+
+    _charset(start) {
       const stream = this._tokenStream;
       const charset = stream.mustMatch(Tokens.STRING).value;
       stream.mustMatch(Tokens.SEMICOLON);
-      if (!misplaced) this.fire({type: 'charset', charset}, start);
+      this.fire({type: 'charset', charset}, start);
     }
 
-    _import(start, misplaced) {
+    _import(start) {
       const stream = this._tokenStream;
       const token = stream.mustMatch(TT.stringUri);
       const uri = token.uri || token.value.replace(/^["']|["']$/g, '');
       this._ws();
       const media = this._mediaQueryList();
       stream.mustMatch(Tokens.SEMICOLON);
-      if (!misplaced) this.fire({type: 'import', media, uri}, start);
+      this.fire({type: 'import', media, uri}, start);
       this._ws();
     }
 
-    _namespace(start, misplaced) {
+    _namespace(start) {
       const stream = this._tokenStream;
       this._ws();
       const prefix = stream.match(Tokens.IDENT).value;
@@ -3515,16 +3515,16 @@ self.parserlib = (() => {
       const token = stream.mustMatch(TT.stringUri);
       const uri = token.uri || token.value.replace(/^["']|["']$/g, '');
       stream.mustMatch(Tokens.SEMICOLON);
-      if (!misplaced) this.fire({type: 'namespace', prefix, uri}, start);
+      this.fire({type: 'namespace', prefix, uri}, start);
       this._ws();
     }
 
-    _supports(start, misplaced) {
+    _supports(start) {
       const stream = this._tokenStream;
       this._ws();
       this._supportsCondition();
       stream.mustMatch(Tokens.LBRACE);
-      if (!misplaced) this.fire('startsupports', start);
+      this.fire('startsupports', start);
       this._ws();
       for (;; stream.skipComment()) {
         const action = Parser.ACTIONS.supports.get(stream.peek());
@@ -3535,7 +3535,7 @@ self.parserlib = (() => {
         }
       }
       stream.mustMatch(Tokens.RBRACE);
-      if (!misplaced) this.fire('endsupports');
+      this.fire('endsupports');
       this._ws();
     }
 
@@ -3747,6 +3747,9 @@ self.parserlib = (() => {
       if (this.options.topDocOnly) {
         stream.readDeclValue({stopOn: '}'});
       } else {
+        /* We allow @import and such inside document sections because the final generated CSS for
+         * a given page may be valid e.g. if this section is the first one that matched the URL */
+        this._sheetGlobals();
         this._ws();
         let action;
         do action = Parser.ACTIONS.document.get(stream.peek());
@@ -4528,12 +4531,6 @@ self.parserlib = (() => {
       [Tokens.S, Parser.prototype._ws],
     ]),
 
-    stylesheetMisplaced: new Map([
-      [Tokens.CHARSET_SYM, Parser.prototype._charset],
-      [Tokens.IMPORT_SYM, Parser.prototype._import],
-      [Tokens.NAMESPACE_SYM, Parser.prototype._namespace],
-    ]),
-
     topDoc: new Map([
       symDocument,
       symUnknown,