function scrollBar(){

var hoogtescherm = document.body.offsetHeight;

var hoogtecontent = document.getElementById('content').clientHeight;

var hoogtetop = document.getElementById('top').clientHeight;

var hoogtebottom = document.getElementById('bottom').clientHeight;

	if (hoogtecontent+hoogtetop+hoogtebottom <= hoogtescherm){
		document.body.overflow = "hidden";
		document.getElementById('content').style.height = hoogtescherm - 172 + "px"
	}
	else {
		document.body.overflow = "visible";
	}

}