Board Thread:Support Requests - Designing Your Wiki/@comment-4437939-20130125054017/@comment-3335785-20130125120106

They've done some minimal styling on the header with CSS. The more important styling is: .WikiaHeader { width:1030px !important; border-radius:20px; border-top:none; } If you add the above to your MediaWiki:Wikia.css (on your wiki), you will see the effects after 10 minutes or so. The colours are easier to change with the Theme Designer tool, rather than messing with them through CSS.

I assume this is within the restrictions of Terms of Use, but I'm not 100% convinced.