Board Thread:Support Requests - Designing Your Wikia/@comment-4618259-20140728210417/@comment-11733175-20140729182022

I wasn't aware it had been rolled out on all wikis on Wikia, but it appears that MediaWiki:Common.css is now imported before MediaWiki:Wikia.css in a single file, in the same way MediaWiki:Common.css and MediaWiki:Monobook.css are imported in the monobook skin.

When the oasis skin was first release MediaWiki:Common.css was purposefully left out, although in the past few months that change was reverted on a select number of wikis (the top 200 WAM wikis iirc). Since then it would seem it's been applied to all wikis.

This means any @import statements in MediaWiki:Wikia.css will cease to work - they will need to be relocated to the top of MediaWiki:Common.css to continue working.