Scratch my post, I think I need to put all of my CSS3 in a separate stylesheet and then import it into my main stylesheet. I got a bit confused so no worries. Thanks for the help.
EDIT: Just been checking out the W3C CSS validator and it does validate official CSS3 such as border-radius. But thanks for answering my question anyway. I'll just use a separate stylesheet for vendor specific CSS3 and import that.