function bepaalhoogte() {

var divh1 = document.getElementById('contentdiv').offsetHeight;
var divh2 = document.getElementById('right').offsetHeight;

if (divh1 >= divh2) {
	document.getElementById('center').style.height = divh1 + "px";
	document.getElementById('right').style.height = divh1 + "px";
	}

if (divh2 > divh1) {
	document.getElementById('center').style.height = divh2 + "px";
	document.getElementById('contentdiv').style.height = divh2 + "px";
	}
}