Not entirely true, heraklees...
The reason I added the top: 0; bottom: 0; to the side elements was because the content div should expand the container downwards as it grows. Sticking the sides to the container, then, should be ok, as long as both top and bottom values are set for the side areas.
To revise my previous comments, the right hand side column should definately be a div... you are going to have content in there (at the moment its just an image, but I assume it will be proper content later). I can see why you have the images in the side areas now... they overlay the repeating background.
Just add "bottom: 0;" to the css for both the left and right elements, and that should sort your problem. I would still make the left hand side a span, force it to display: block; to keep it semantically neutral. Once you've done that, you should be good to go.
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