RE: Usability and Font Sizes
Please, whatever you do, don't use small, large, x-large, etc.! The actual sizes vary from browser to browser what looks normally sized in IE looks microscopic in Mozilla, or vice versa. [The .NET Guy]
Hmm... I just did a quick test. Using the em measurement is identical in both browsers as expected and while the named sizes are not exact, they are very close and are indeed still relative to the browsers text size:
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