Pixel-based (and point-based) font sizes won't let you change the text size at all in IE/Windows, which screws anybody with less than 20/20 vision at the xx-small size.
Originally Posted by M. Johansson
Your issue here is most likely that IE is in quirks mode, which actually makes IE render fonts larger than it's supposed to. To get the same result in all browsers you can do something like this:
Originally Posted by Ethics
/*font size for IE users*/
/*font size for all other browsers*/