diff -r 000000000000 -r 6474c204b198 toolkit/themes/windows/global/toolbarbutton-aero.css
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/themes/windows/global/toolbarbutton-aero.css	Wed Dec 31 06:09:35 2014 +0100
@@ -0,0 +1,12 @@
+/* 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/. */
+
+%include toolbarbutton.css
+
+@media (-moz-windows-default-theme) {
+  toolbarbutton:-moz-lwtheme:not([disabled="true"]) {
+    color: inherit;
+    text-shadow: inherit;
+  }
+}