How to set div height dynamically based on user's browser dimensions
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Using this example:

http://jsfiddle.net/FhWxh/

How do I make the "sidebar" 100% of the height of the user's browser (minus 50 pixels to leave room for the header)?

I believe it's possible to get the user's browser height using javascript and insert it dynamically into the css, but I don't know how to do that.   
