I have a test site up right now (this was a quick mockup I made)
http://www.foreverbroken.org/user/xoop/
if you have firefox you can change the css file to blank and see what its like without the any css
here are the files
the base
http://www.foreverbroken.org/files/csstheme.zip
the mockup I made.
http://www.foreverbroken.org/files/cssleo.zip
the base theme without and content is xhtml trans. compliant