In an ideal world, a simple “clear:both” applied to the footer <div> would be enough to clear the content and allow the footer to flow across the bottom of the page. However, Internet Explorer 5 and 5.5 will not tile the background image to the very bottom of the containers unless there is a new item that is clear of the floats but still inside the containers. For this reason, an empty <div> is used, and styled with an ID selector to "clear:both". It is also given a height.
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