CSS gone! Did selectors change?

Or did I screw something up?

I went to look at my calendar today, and all my custom styles are gone! I had some overrides in my theme css file, and none of them are being used anymore.

The styling of the stock calendar has changed significantly, so I thought maybe some of the elements have changed names. In Firebug, my styles are crossed out as though they've been overridden.

The only thing that could have touched the calendar is OG. I think I changed my event content type so groups could have their own calendars.

I haven't dug in yet to ferret out what's gone wrong, and it's only a couple of declarations that need to be fixed, but it's weird, and I wondered if anyone knew any scoops.

If nobody knows, I'll take it as a sign from God that I need to get hoppin’ on a re-design. ;-)