Board Thread:General Discussion/@comment-5377726-20171105050923/@comment-9605025-20171105235756

As a reference to what Fngplg mentioned, see this help page.

Personal CSS gets the highest priority of all stylesheets. As such, it overrides anything in the site CSS. Even if personal CSS works, changes in site CSS may not work if overridden by following CSS in the same stylesheet. Note that, due to how Wikia handles stylesheets, CSS on different pages may actually be on the same stylesheet. If you care to know more, expand the following section.

More

 In order to reduce the number of load requests per page, Wikia actually concatenates the various CSS. All default CSS from extension defaults and Wikia's own global settings are applied using a single file, Qualaroo.scss. This is actually Sass, not CSS. This file is loaded first to allow site and personal CSS to override the default styles.

For site and personal CSS, the stylesheets concatenated depend on the skin in use. As expected, between the two, site CSS is loaded first so that it may be overridden by personal CSS. If the wiki was created before or during July 2014, the site CSS consists solely of the CSS on the skin-specific page. If the wiki was created after July 2014 (or the change has been enacted upon request), the site CSS first contains the contents of Common.css and then the contents of the skin-specific page. For personal CSS, global.css (personal CSS for all Wikia sites) is first; followed by common.css (personal CSS for all skins) and then skin-specific CSS.

Knowing how these pages are concatenated is particularly important if you are going to use @import. This is because @import only works if there is no preceding CSS in the same stylesheet. In other words, only comments, blank lines, and other @import can precede it.