When I got home last night I noticed that my previous tab repairs for Opera 7 and IE on Windows had caused new problems for IE and Camino on Mac OSX. I suspect that the font sizes were rendering differently, so that what was taking up the ideal amount of space on one system was overflowing and pushing stuff around on the other. So I tried the old trick of sticking a red border around all my divs until I’d figured out what exactly they thought they were doing.
I ended up tweaking the pixel height of the banner some more, and now it looks fine in every browser created since the Bronze Age. Major user changes in font size would probably throw it all off again, but the worst that would happen would be the submenu floating up to some weird place. Netscape 4 is still a problem, since for some reason it doesn’t render the tabs as links on the main page or the blog. The rest of the pages are usable.