first, get rid of the multiple css files. Merge if you can but more than one will only be a constant hindrance.
Second, get a copy of firefox, with add-ons like firebug. It will tell you where the divs are that you can set your existing header "parts" into. Zen is the engine to the car. Once you get the motor mounts right the engine will fit inside any body. You can use the firebug to find out the size and spacing of those motor mounts.