Board Thread:Support Requests - Getting Technical/@comment-31309975-20130403162957/@comment-10688548-20130403184546

You can put whatever you want in Wikia.css. However it'll only affect the default "Wikia"/"Oasis"/"New Wikia Look" skin.

Common.css would theoretically affect all skins on the site. In fact it even says that it does so on every new wiki. A lie! It only affects the old style Monobook skin. As such, "common.css" is "common" to exactly one skin, and identical in function to Mediawiki:Monobook.css which should apply to only Monobook.

Users who want to have universal CSS that does indeed affect both skins can place the CSS in Common.css then import it to Wikia.css to emulate the function. This is what I've done on my w:c:wolfenstein:Mediawiki:Wikia.css (see the first bit of code).