diff --git a/mozilla/layout/html/tests/css/IMPORTANT.css b/mozilla/layout/html/tests/css/IMPORTANT.css
new file mode 100644
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+++ b/mozilla/layout/html/tests/css/IMPORTANT.css
@@ -0,0 +1,35 @@
+/*
+ * The contents of this file are subject to the Netscape Public License
+ * Version 1.0 (the "NPL"); you may not use this file except in
+ * compliance with the NPL.  You may obtain a copy of the NPL at
+ * http://www.mozilla.org/NPL/
+ *
+ * Software distributed under the NPL is distributed on an "AS IS" basis,
+ * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the NPL
+ * for the specific language governing rights and limitations under the
+ * NPL.
+ *
+ * The Initial Developer of this code under the NPL is Netscape
+ * Communications Corporation.  Portions created by Netscape are
+ * Copyright (C) 1998 Netscape Communications Corporation.  All Rights
+ * Reserved.
+ */
+// Combinatorics for !important
+Important {
+  color: purple !important;
+  padding: 2px;
+}
+Important {
+  color: purple ! important ;
+  padding: 2px;
+}
+SomewhatImportant {
+  color: purple ! foo;
+  padding: 2px ! important;
+}
+NotImportant {
+  color: purple !foo
+}
+NotImportant {
+  color: purple ! foo
+}