CSS question

I've used your validator with my html pages to get them perfect , I also used the css one and got no errors or warnings. But I dont get that statement saying I can use your logo. I see 
To work as intended, your CSS style sheet needs a correct document parse tree. This means you should use valid HTML. 

I'm a little slow on the uptake, do I need certain format? Does it need to link to the HTML when it checks it? Or does it always say that on the page?

Thankyou for your help,

Harry Bernstein

gm2ice@mindspring.com