Board Thread:Support Requests - Designing Your Wiki/@comment-5076341-20121212184639/@comment-188432-20121213062239

Hate to be the Debbie Downer here, but realistically you can't do that much to affect the overall style of a wiki without being an admin. You can basically only create and change templates, but  if you create these templates through inline CSS, the uniformity of your design will be almost instantly compromised by users who, trying to be helpful, take away a right border on template A, but forget to do so on the should-be-styled-the-same template B.  Before you know it, the green color palate you'd carefully worked out is now red on one template, purple on another, and yellow on a third.

If you really want your site to look good, you must style it through CSS (that is, by using MediaWiki:Wikia.css and MediaWiki:Common.css), which means you have to be an admin.