May I ask why you decided to not float the middle div just like the others?
Anyway thats what I did, also your code was very messy imo that’s why I couldn’t understand what was goin on the first time around. It also isnt very semantically correct. You had the middle div (content) after the div that you wanted to display last in the html.
Remove the margins on the divs and just float them (it does the same thing you were attempting to do with the margins and padding)
Tell me if I translated what you wanted horribly wrong or if it helped you :)