font-family:Verdana, Geneva, sans-serif;
EDIT: It turns out I had the above problem all wrong, and it's got nothing to do with FF fumbling the padding attribute. It's the SCROLLBAR.
IE takes the scrollbar into account when doing a right:0, while FF does not. In FF, the scrollbar overlaps on the span.
I'm guessing I'm kind of stuck with the problem and there's no obvious solution to it, right? I mean, there's no way to tell FF to "take the scrollbar into account when applying right:0"?
Oh well, thanks anyway. lol