OK, firstly, in future you should include all of the code, as the problem you have lies in the part that you didn't include
Basically, the reason height:100% isn't working as you would like, is because it is extending to the full height of the parent element, which is the div with the id of 'contentbox'. You want it to be the same height as the 'content' div.
Hope that was a help 
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