This is the page with little content height but the side border images still continue to the window bottom.
This would be the containing div for all page content. The images are all background-images so that scrollbars are not created unless the content needs them.
The side background images extend to the bottom of the window, whatever height it is, if the content does not use the window height and no vertical scrollbar is created. They also extend to the bottom of the content div if it exceeds the window height, creating a scrollbar.
In this case the content div has content which does not exceed most window heights and the side background images would still go to the window bottom. In fact there is one set of side background images in position: absolute divs for the small content div height and another set of side background images in divs floated left and right for the situation where the content div might exceed the window height.
The position: absolute divs with height: 100% on their own will only go to the bottom of the window and if the content exceeds the window height and you scroll, the side background images scroll up leaving a space below. The divs floated left and right will extend the side background images to the bottom of the content, even if it exceeds the window height, and will cover any space if the other side background images scroll up, but won't reach the window bottom if the content is small, so you need both sets of side background images to cater for content either less or more than the window height and to remain flexible in height.
The side images are 17px wide and 13px high, repeating vertically and the body background image is 1600*1200. The width is also flexible.
See this page for content with more height.