Update userChrome.css

Author: Aris-t2

current/userChrome.css

@@ -726,7 +726,7 @@
 */
 
 /* @import "./css/tabs/tab_audio_icon.css"; /**/
-/* @import "./css/tabs/tab_audio_hidden.css"; /**/
+/* @import "./css/tabs/tab_audio_icon_hidden.css"; /**/
 /* @import "./css/tabs/tab_audio_icon_favicon_hidden.css"; /**/