Howto make the Dokeos footer float

I don't know about you, but I really don't like the Dokeos footer moving around the screen when there's less content. Luckily, CSS offer an easy way to change this. Let's say I want to update the css/dokeos_classic/ theme. The rule, as always, is to make a copy of the directory that is the closest to what I want, and only work on a copy, so I'm going to do that.