I've just started to learn CSS and this is probably a stupidly simple question but for the life of me I can't figure out how to do this. I have a two column website, one column is the navigation the other is content. The nav and content are in a "wrapper" div with the content floated to the right. The navigation has a green background colour and I want the green to expand downward as the content grows. Right now if content goes past the bottom of the navigation, the green stops under the last link. I don't have the code with me right now. But as an example of the effect: Imagine a two column table. As the content column expands down, so does the nav column auto-filling with a green background. Since the content expands the wrapper div, I thought, height: 100% would work, but that didn't do anything. Any help would be appreciated. Thanks!