I tested it under linux (opensuse 11.2) and firefox 3.5.9.
Some problems appears on contact form ("contact goes out of the green window)
Some problems appears on thick boxes and cells on options page
Last thing, you can see that the pages appears "untitled" : it seems that your pages doesn't have any
title (speaking of HTML) : you should add some in your pages code (but since you say the website is in W.I.P, it 's certainly a feature you thought about)
HOpe it helps !