Some things seem to be missing at the moment:
I confirmed this in private/incognito windows in Firefox and Chrome, and in plain old Safari (no customizations and, apparently, no prior visits to this site). It happens on main and meta. Question pages appear normal except for this:
I checked a few other sites and haven't seen it anywhere else so far. I don't know if this is relevant, but I think we do not yet have the new base CSS layer that's being rolled out -- or, at least, we don't have the new-style profiles, and those depend on that new CSS. So perhaps we're in transition and this will sort itself out in an hour or two (or 6-8)?
Update: Ok, now it's getting weird in here...: