Div height

[Davide]

Ok, so i have 3 div's.

One of them is the main area of my website:

<div id="contentmain">
        
        	<div id="contentleft"> </div>            
            <div id="contentright"> </div>
            
            <div id="content">       
        
            </div>
            
        </div>

The other two, content left and content right are just divs that hold the image with the border. They only appear on the top because i specified their height to be 100% but contentmain's height is not set. How can i make the div's work without changing contentmain's height (since it must resize according to content).

Note: contentleft floats to left and contentright floats to right.