CSS Aha! Moments

I've been programming computers for many years, but only recently have become aware of the new wave of interest in web design standards. Things like why ems are almost always better than pixels, and why not to use alt for tooltips.

This is all new stuff for me, and as I go along I'm going to capture what I'm learning in this little web app: CSS Aha Moments. Add your own CSS Aha! moments if you like!