Here's the problem with the website not displaying correctly in Firefox, according to the people who matter *.
It's one of these weird mixes of styling where the site's half done in CSS (good and proper separation of content from text) and half done with styling on the page.
Which is weird, cos a nice clean design like that can easily be done with CSS + strict XHTML (
and not using tables for main site layout ).
* Firefox doesn't need XHTML Strict, obviously. But we may as well get it right
If you want default markup checking,
here it is.