first, any books out yet? I’ve searched, but no books even mention a version number.
second, in (x)html there’s a DTD at the top of the document that lets the browser know what version of (x)html it is. Is there something like this for CSS3?
@Declan1991Sep 06.2008 — #CSS 3 isn't fully defined, the latest work can be found [url=http://www.w3.org/Style/CSS/current-work]here[/url] and no there aren't any things that allow you to specify which version of CSS you are using (not that I know anyway).
The main problem is browser support, basically no browser supports CSS 3 fully, and even CSS 2 isn't fully supported by all the major browsers.
@michaellunsfordauthorSep 06.2008 — #Oh, well. I'm trying to use opacity, but validator whines about it being outside of CSS2, but is included in CSS3. Perhaps a few more years ;-)