This seemed like a simple problem at first, and it probably is, just need a push here.
I would like to take the body background related css, clean the body from any background-css. and put the copied css inside a div instead.
var _body = document.getElementsByTagName("body");
var _copy_of_background = _body.background;
_body.background = '';
document.getElementById('theDiv').style.background = _copy_of_background;