Sidebars overrun bottom border

I’m using a fluid 3-column theme adapted from one I found floating around out there. On posts where the sidebars are longer than the post content, the sidebars run over the bottom margins. I am completely at a loss. The problem existed in the original theme, and I emailed the designer but never heard back. My site is here:
http://dvp.btcnews.com

You can see the problem here:
http://dvp.btcnews.com/?page_id=2

I am not a CSS whiz and I’m sure this is something simple but I’ve been picking at it off and on for what seems like decades with no luck. Any help will be profoundly appreciated.