diff -r 000000000000 -r 6474c204b198 toolkit/components/help/content/platformClasses.css
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/components/help/content/platformClasses.css	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,13 @@
+/* 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/. */
+
+%ifdef XP_WIN
+.noWin, .mac, .unix { display: none; } 
+%else
+%ifdef XP_MACOSX
+.noMac, .win, .unix { display: none; }
+%else
+.noUnix, .win, .mac { display: none; }
+%endif
+%endif