Thanks for the answers guys, but I think I didnot explain my problem very well:
this is my code:
Well, everything works just fine if I DO NOT use <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" , but if I do use it, I mean, if I start the page as it is up here, the CSS does not work anymore, well it works but not as it should, at least in Firefox. IE 6 it works as it has to.
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<meta http-equiv='Content-Type' content='text/html; charset=iso-8859-1' />
<link href='style.css' rel='stylesheet' type='text/css' />