Board Thread:Support Requests - Designing Your Wiki/@comment-32849916-20170819144531/@comment-9605025-20170820173137

Two things:
 * 1) Because you have a new wiki, you should be placing all this CSS on Common.css; not Wikia.css. For the reason why, see here and here.
 * 2) To expand on Henstepl's comment, site-specific CSS is concatenated into a single file (see here). As such, an error in any site CSS may result in unexpected behavior from all site CSS. This also means that import statements only work if placed on Common.css (for new wikis). There is also a similar situation for personal CSS except that global.css is at the top (see here).