>>>>In the course of learning CSS, I've come up with a theory about
>>>>something that I'd previously noticed (and found bothersome): Some
>>>>web sites won't let me copy text.
I've noticed this in IE 6 on Windows as well, although you can use
Ctrl+A to select all the text, even on the Webstandards.org page. Or
you get different results by placing your cursor and double-clicking.
My guess is that it's an IE 6 issue, not a CSS issue. I've noticed
that IE 6 also crashes a lot when I try to print pages that use CSS,
whereas I have neither of these problems with Netscape 7.