RDFa and CSS

I'm trying to figure out how to tie RDFa annotations into CSS; 
unfortunately, I'm just beginning with RDFa and I have even less 
understanding of CSS.

We've started looking into RDFa because we want to use it in our 
applications. I was looking at some example markup that a coworker was 
working on and noticed that you would duplicate an @rel with an @class, 
something like

    ... class="foo" rel="foo" ...

so that someone could define a foo class in CSS and format the fragment. 
Is there a way of having a more direct connection between the RDFa 
annotations and CSS? The only thing I've been able to find is a few docs 
on Fresnel, but I'm not sure we can assume someone's going to have a 
capability to process Fresnel in their browser.

Brian