The CSS Samurai group of TheWebStandardsProject put together something called the BoxAcidTest which is an insane, though 100% standards compliant, CascadingStyleSheets test.
There's a good article on various browsers' support at http://webtools.com/story/browsers/TLS19981223S0003. Notice how much Netscape is a Bad Browser, and BadBrowsersMustDie. Then again, so should OperaBrowser and InternetExplorer. Actually, IE 5.0 for Mac renders this perfectly. For Windows, IE5.5 is still busted. Go figure.