I'm doing multiple stylesheets because I haven't found a way to keep the page stable if the viewer resizes: hit a link and it's back to square one, not a good look.
So: I've tested on a mac for heights 'over 1000px', 'under 880px', and 'under 770px'—not at work this weekend.
If you happen to have a screen with a height of 900px or 960px—you'd be in a group which is anywhere from 10% to 23% of net users, depending on your statistics source—I'd especially like to hear from you. And any and all IE users.
Hopefully, you'll have a worst-case scenario with lots of height taken up by the browser's toolbars.
Minor css problems with Safari and esp Opera are known.
Major script rendering problem with Opera known also.