Me and Octo did some digging. It's a cache issue. The CSS file you're getting is from about 3 days ago. I have no idea why that's happening. I've told the forums to refresh all its caches, and that doesn't seem to have fixed it.
I know it's annoying, but you could clear your caches on your side, and see if that helps. If you're air, and don't want to clear EVERYTHING, you can clear caches for one site only,
as described on this tutorial.
However, I'm kinda tempted to ask one or two of you to not do that, just so I can test to see if/when it fixes itself.
Yeah, sorry