Cannot stretch div to bottom of the page

Hey everyone. Simple (I hope) problem here with a div. Here is the site I am working on:

I am trying to pull the left sidebar div all the way to the bottom, but for some reason it just won’t go. There doesn’t seem to be anything restricting it, so I can’t figure out where to go from here. Thanks for your help.

Here is what I would do:

You already have a background image so just make it follow the columns.

“The embarassingly simple secret…”

True words right there, I can’t believe I didn’t think of this after seeing so many other pages done the same. Thanks for the link!