CSS Validation?

CSS Validation?


Hi all,
I'm working with jQuery UI as part of a project and it (the project)
needs to be fully W3C compliant (in both XHTML and CSS). My XHTML and
my own CSS files validate correctly, however when I try to validate
the themed CSS files that I've downloaded from here I get nearly 40
errors telling me that certain properties don't exist, and there are
also a few parse errors.
Can anyone give me any advice? Has anyone else noticed this issue?
Thanks in advance!