Thank you for noting that. I'm going to test it on some mac browsers right now.
Also, I've taken the ads down. I have the site up for review at numerous sites, and everyone said I just wanted it reviewed so I can get ad impressions... so I've taken them down for now. I need reviews.
The page is now XHTML transitional, thanks for letting me know! Forgot to validate it before the review
Great info - easy to get to and read. I would possibly work on your color combo some or at the very least - the logo's color as it tends to fade away in the header - especially on my laptop that seems to be so bright that light colors disappear. (not sure why - its a Dell - if that explains it)
I like the layout of the site alot. You just need more content of course, and each entry should show real examples (either screenshots or with actual CSS) of the different property values. Also, clicking a property should show only that property. For example, clicking "border-width" should show only border-width, not the page for all border properties. This makes it cleaner. But that page should have a link to the Border category, a Back link, and perhaps prev/next links.
Examples are the most important thing though. W3.org is an excellent resource for CSS, but it lacks examples. It's meant to be viewable by anything so its attempts at examples are actually just ASCII art and they look ridiculous.