Board Thread:Support Requests - Designing Your Wiki/@comment-24357860-20140101204933/@comment-5007040-20140102152241

You can't create an own Wikia wide theme. However you can make a different background, wordmark etc. for your wiki. You can do this in Special:ThemeDesigner like Akamichi said. You can find it through clicking on admin on the bottom of your screen and then click on ThemeDesigner.

Hope this helps you!