function getWindowHeight() {
	var windowHeight = 0;
	if (typeof(window.innerHeight) == 'number') {
		windowHeight = window.innerHeight;
		}
		else {
		if (document.documentElement && document.documentElement.clientHeight) {
			windowHeight = document.documentElement.clientHeight;
			}
			else {
			if (document.body && document.body.clientHeight) {
				windowHeight = document.body.clientHeight;
				}
			}
	}
	return windowHeight;
}
	
function pasHeightAan() {
	//aanroepen door:  onload="pasHeightAan()" onresize="pasHeightAan()"
	//var scrH = screen.availHeight ; //obv schermhoogte
	var scrH = getWindowHeight() ; // obv beschikbare browserruimte
	//contenthoogte
		//factor bepalem
		var cF = 0.8
		var tF = 0
		if(scrH < 200)  { var cF = 0.9 ; }
		if(scrH < 400)  { var cF = 0.9 ; }
		if(scrH < 500)  { var cF = 0.9 ; }
		if(scrH < 600)  { var cF = 0.8 ; }
		if(scrH >= 600) { var cF = 0.7 ; }
		//hoogte brekenen
		var MiddelHeight = scrH * cF ; 
		//hoogte toekennen
		var div1 = FrameContent ;
		div1.style.height=MiddelHeight;
	//topmargin 
		//factor bepalen
		if(scrH < 400)  { tF = 0.00 ; }
		if(scrH < 500)  { tF = 0.00 ; }
		if(scrH < 600)  { tF = 0.04 ; }
		if(scrH >= 600) { tF = 0.07 ; }
		//topmarin berekenen
		var MarginTop = scrH * tF ;
		//marge toekennen
		var obj = FrameMain ;
		obj.style.top=MarginTop;
}