Screenshots don't give much information. It is a big help to see the code running live. That is why support people are always asking for a direct link to the problem. I explained that bfore.
Ok, you've got insane amounts of stuff stacked up, so the backdrop.png is running out of height. You'll have to make a taller image and change the css to suit. Either that or split it into two images (which still involves css changes, obviously).
I dont have insane amounts of anything stacked up anywhere on that site, so unless you can clarify that, I have no idea what your referring to. If your referring to the chatbox I have there, there is nothing insane about it, its one item and its put in a board descrip like that so guests cannot see it. There is nothing there that can be "split".
as for the css, 2.0 theme code has changed extensively versus prior theme code so I have no idea even where to begin even looking for where that image may be because on older themes, thats not an image, its simply a color you choose for that particular area. I pretty much had a feeling that there was an image involved in these two themes or that area would have just expanded to fit the chat box like all my other custom themes do. Since theme code has changed so much, no idea where its even listed or what it was called.