function setHeight() {
	if(window.innerHeight) {
		var wH = window.innerHeight - 318 - 58;
	} else {
		if(document.body.offsetHeight) {
			var wH = document.body.offsetHeight - 318 - 58;	
		}
	}
	document.getElementById('contentback').style.minHeight = wH+"px";
}

window.onresize = function() { setHeight(); }