hcard void with css?

Hey guys, to further enhance my local listing I want to add hcard code. Because this has to visually display, does anyone know if I add some CSS attributes to the code if it will make the hcard information void to Google, or worse - make it look like I'm trying to do something dodgy to the code and get penalized.

I'm also wondering for those using hcard, do you recommend placing it on every page of the site? i.e. in the footer. Or is it best on index page or just as powerful being only on the contact page?

Thanks in advance for any help!

Anyone know? Or anyone experienced results when adding it to their site?

Thanks.