function maxHeight() {
	var h;

	if (window.document.innerHeight) {
		h = window.document.innerHeight;
	} else if (window.document.documentElement.clientHeight) {
		h = window.document.documentElement.clientHeight;
	} else if (window.document.body.clientHeight) {
		h = window.document.body.clientHeight;
	} else {
		h = 800;
	}
	return h;
}
function maxWidth() {
	var w;

	if (window.document.innerWidth) {
		w = window.document.innerWidth;
	} else if (window.document.documentElement.clientWidth) {
		w = window.document.documentElement.clientWidth;
	} else if (window.document.body.clientWidth) {
		w = window.document.body.clientWidth;
	} else {
		w = 1300;
	}
	return w;
}
function setBackgroundSize(){
	var bg=document.getElementById("background");
	bg.style.height=maxHeight();
	bg.style.width=maxWidth();
}
window.onresize=setBackgroundSize;