A main content area and a sidebar with each having different colors and both maintaining the same height such that they expand vertically with the content (with

A main content area and a sidebar with each having different colors and both maintaining the same height such that they expand vertically with the content (without having to hard-code pixel values). I saw a page showing how it could be achieved using only divs, but really, it was a complete rube goldberg machine, the sole purpose of which, seems to be to adhere to the religion of not using tables. I get that table layouts have their own issues but I think its silly to be dogmatic about refusing to use them where it's clearly the best hammer to drive in that nail.