CSS W3C compliance for jquery

Just recently I studied about HTML W3C compliance and started understanding its benefits. But when it comes to CSS W3C compliance, is it really possible for a web 2.0 website (like:开发者_JS百科 boxee.tv, corp.ign.com, guifx.com/store, guifx.com/_product_61775/Deana# ) ? I found that jquery ui's CSS did not pass the validation (link) because of css hacks. Are there any other w3c compliant UI libraries which work in all popular browsers?

On a bit different note, can you please tell some good W3C compliant ways to achieve rounded corners?

Thanks,

Akshey

CSS W3C compliance, is it really possible for a web 2.0 website?

Yes. (Depending on how you define 'Web 2.0', it is a very vague term that is more suited to marketing people than developers.

On a bit different note, can you please tell some good W3C compliant ways to achieve rounded corners?

https://stackoverflow.com/search?q=valid+rounded+corners