Replying to: Eric
Better that "not wrong", I also think that IE behaviour (zoom relative sized text and not fixed sized text) was the good one.
Anyway, to answer Stephane:
Stephane, text zooming is only a side effect of em sizes. In your article you miss the main point of em size: letting the user choose the correct size at start, without zooming.
With em, the user can tweak is configuration and choose something adapted to his abilities and preferences. With pixels, the author choose the size for you (why ? on what basis ?)
The ability to zoom text is only a side effect. You should not have to zoom a (...)