Saw this really clever trick to scale a box to fill its container on Devign.

Hello world

Basically, the outer div is "position: relative" and the inner div is "position: absolute" with top, bottom, left, right defined but no width or height. So like in Interface Builder, the inner box is anchored to the outer box and stretches with it. Sweet!

Fails in IE6, but works in IE7 and everywhere else!