Board Thread:Watercooler/@comment-24692230-20180104153506/@comment-24757753-20180104172634

CSS pages that are part of a script might as well be moved to the MediaWiki namespace without a redirect, since their only usage can be updated easily.

Stand alone CSS pages, however, can be imported with various methods in site and user CSS pages. Without server-side redirection in place (like for JS pages), moving these can cause issues for existing imports, so I think it's best to leave them where they are. Besides it not being the "correct" namespace for the pages, I don't think there's any real need/benefit to moving them, compared to the downside of causing some people issues.

> I'm not sure if the implementation only works for .js pages or whether it works for .css as well.

As far as I know, it only works on pages ending in ".js" (I think it's tied into the content review code). If a server-side redirection like that could be put in place for CSS too, I'd be all for moving them across (though preferably by a proper move preserving history, not just copy-pasting).

ResourceLoader will follow actual redirects (for any type of page, not just JS) and return the target content (just tested this), but that won't work for  imports, sadly.