function headerchange() { 
	var headerpic = document.getElementById("headerpic");
	var whichpicno = Math.floor(Math.random()*7);
	var sourceheader = "fileadmin/tvtemplates/media/header-" + whichpicno + ".jpg";
	headerpic.setAttribute("src",sourceheader);
	}
	window.onload = headerchange;