Board Thread:Support Requests - Designing Your Wiki/@comment-5218827-20191014191753/@comment-9605025-20191015024123

The wiki was started before the switch to the current CSS arrangement. Although staff thought it was okay to remove the corresponding notes from the CSS help page, this difference still applies to old wikis. However, thanks to some initiative on my part (some self praise there), the information has since been restored to the help page. See Help:Community_CSS_and_JS. - Edit:

An alternative to enabling this new CSS arrangement, you could just import Common.css in Wikia.css. In fact, your Common.css has the necessary import statement already; it is just in the wrong stylesheet. After all, there is no point in having a stylesheet import itself.