KenB - 1:32 pm on Feb 3, 2010 (gmt 0)

One reason I use a fixed PX instead of a dynamic size like EM is that I have a pixel perfect design. If text scaled independently from the rest of the page there would quickly be a lot of layout issues. By all sizes being defined in PX the whole page scales together and most of the modern browsers properly zoom in on the whole page rather than just the text, which keeps text flow proper.