I\'ve read a lot about the pros and cons of sizing with either relative or absolute font sizes. Fixed sizes don\'t zoom in IE6 but that\'s not much of an issue these days. A
As explained in this CSS font size article:
Ideally? The very best unit of measure is NONE AT ALL! Let the user-agent determine the display according to the user's preference - BUT! We also know that with most designs, this is not a very practical approach. Personally? I prefer the "mix 'n match" flexibility of .em and .px - As user-agents become more "user-friendly" designer sizing will NOT be as potentially problematic OR controversial as it stands now.
Do not forget though relative font size can be used for other things than... font size!