Board Thread:Support Requests - Designing Your Wiki/@comment-876677-20170131221136/@comment-168424-20170131230803

Looks like you have to use Javascript: http://lea.verou.me/2012/05/text-masking-the-standards-way/

Javascript is not much scarier than CSS if you have good examples. Also, you can get help at Dev wiki.

Additionally, to quickly test CSS and Javascript without affecting wiki-wide, use Special:MyPage/wikia.css and Special:MyPage/wikia.js (on your wiki). Most Javascript can be thrown inside  code here   to get it to work on Wikia wikis.