Even W3c is not Valid in unicorn validator?

If I am not wrong W3c.org is responsible for html and css standard but its own site is not valid with its own validator , Can anybody clear what is this??

http://validator.w3.org/unicorn/check?uc开发者_如何学JAVAn_uri=www.w3.org%2F&ucn_task=conformance#

They are using CSS 3 (with some vendor specific experimental implementations of certain properties that they have decided are well enough supported to use) and you are testing against CSS 2.1.

Validation is a tool, not a competition. There are plenty of good reasons to deviate from the specification providing you understand the consequences of doing so (for the specific way in which you deviate).

The validator is validating against CSS 2.1, however the w3c site uses CSS 3 (plus some non-standard browser specific extensions).

EDIT: Also, it doesn't really matter if the CSS validates, as long it complies to the general syntax rules, so that browsers still can read it and just ignore any selectors or properties it doesn't know.