Why are fixed font-sizes evil?
"There are lots of fancy CSS sites out there made by CSS gurus who have not thought about what happens when the text gets bigger than normal. These websites struggle when a visitor uses bigger fonts, and it never letting sizes go below a minimum font size, no matter what the page author has put in his style sheet. The consequences are sometimes quite horrible.
Internet Explorer takes absolute font sizes (specifying font-size in pixels or points) and fixes the font size preventing resizing. However people usually increase the font size because the can't read the text at the default. The end result is an unreadable and unusable website for that visitor.
A good website design will allow a user to scale the fonts up and down to fit the visitor's preferred size.
Internet Explorer has an option to ignore all specified font sizes on a page with Tools > Internet Options (General Tab) > Accessibility (button). However the existence of a user option (even if it had been right there on the toolbar as in Opera, rather than being knee-deep in some menu in the hope that no user would ever find it) is any excuse for authors to add counterproductive rendering specifications in their documents.