diff -r 000000000000 -r 6474c204b198 dom/webidl/CSSStyleSheet.webidl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dom/webidl/CSSStyleSheet.webidl	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,22 @@
+/* -*- Mode: IDL; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/.
+ *
+ * The origin of this IDL file is
+ * http://dev.w3.org/csswg/cssom/
+ */
+
+interface CSSRuleList;
+interface CSSRule;
+
+interface CSSStyleSheet : StyleSheet {
+  [Pure]
+  readonly attribute CSSRule? ownerRule;
+  [Throws]
+  readonly attribute CSSRuleList cssRules;
+  [Throws]
+  unsigned long insertRule(DOMString rule, unsigned long index);
+  [Throws]
+  void deleteRule(unsigned long index);
+};