I went to www.w3.org/Style/CSS using Opera 7.03 and it froze. I tried it again. It froze. One more time, just to be sure, and it still froze.
I’m a fan of Opera, but it seems strange that the page which describes the standards Opera claims to adhere to so strictly doesn’t work.
Of course, the page looks awful in IE 6.0, but Mozilla renders it like a champ.