Controlling Div Heights

This one had puzzled me for some time. I would create a div container on a web page, then assign a height to be 100%. Sometimes it would work, other times not.

The reason is because the height based on % is determined by the parent object. If the parent object doesn't have a defined height, the child setting degrades to auto. For a fuller explanation and examples read papabaer's CSS 100% Height DIV's tutorial.