Broken floats in CSS

My left sidebar goes further down the page then the forums. Because of this, the custom background colors I'm using for the main body and a different color for the "main content" area stops at the last forum entry. The left sidebar extends down into the body background color. The float needs to be cleared so as to allow the main content area to extend down alongside the left sidebar.
I think I made that too complicated. . . .
Second try . . .
You're floating #lefty, and floating #content, but depending on a huge side bar extending well below the content, you'll notice that the floats are not cleared.

A simple CSS amendment will fix this.
Cliff