Liquidly extending CSS boxes

I just had an “eureka” moment about how to reclaim a long envied capability of table based designs for the world of CSS styled semantic markup. Namely, it has thus far been considered impossible to create a columnar layout where the higher of the columns dictates the height for both colums in a truly liquid fashion. Ugly hacks have been invented to circumvent this, but a satisfying solution had yet to be proposed so far.

Well, take a look at liquidly extending CSS boxes.

This technique is so obvious that I hardly dare declare myself the discoverer – surely, someone else must have thought of this before. Nevertheless, I have not seen it pusblished anywhere before.