CSS: have a div after an absolute positioned div

Answer 1

If you're using absolute positioning but you don't know the height of what you're positioning, that is a problem that HTML isn't very good at solving. I have seen (and probably written) hacks where JavaScript is used to position an element based on the offsetHeight of another.

But you might be better off using the CSS float property instead of absolute positioning. float and clear are pretty good for positioning things like you want, without sacrificing automatic page flow.