left sidebar
This is the main content area
Here is some text in the center column
To make the sidebars "appear" as though they go all the way to the bottom of the column, you would use a custom background image for #container that had the background colors of the sidebars. Your background image would be 1 px tall and then you would set the repeat.
Example:
#container {background: url("images/container_bg.gif") repeat-y;}
Any questions? Contact jzelazny at sandboxdev.com