I think I'm about to feel like a fool. I had forgotten that CSS isn't part of the DOM, so of course domready could be true before all CSS is loaded.
Perhaps the larger issue here is that for code like this, which relies on
the presence of CSS, you can't/shouldn't use window.addEvent('domready'),
but rather window.addEvent('load'). I'm so used to using domready that I
didn't give it a second thought. I'll run a few tests...
