var tmph = "";
var tmpw = "";


function resize()
{
	var afb = document.getElementById('achtergrond');
	var midden = document.getElementById('midden');
	var footer = document.getElementById('seo');
	
	if(afb == null)
		return false;
	
	
	if(tmph == "" && tmpw == "")
	{
		tmph = afb.height;
		tmpw = afb.width;
	}
	
	afb.style.height = "1px";
	afb.style.width = "1px";
	
	var viewportwidth;
	var viewportheight;
	
	if (typeof window.innerWidth != 'undefined')
	{
		viewportwidth = window.innerWidth,
		viewportheight = window.innerHeight
	}
	else if (typeof document.documentElement != 'undefined'	&& typeof document.documentElement.clientWidth != 'undefined' && document.documentElement.clientWidth != 0)
	{
		viewportwidth = document.documentElement.clientWidth;
		viewportheight = document.documentElement.clientHeight;
	}
	else
	{
		viewportwidth = document.getElementsByTagName('body')[0].clientWidth;
		viewportheight = document.getElementsByTagName('body')[0].clientHeight;
	}
	
	//alert(midden.offsetHeight + "  -  " + footer.offsetHeight);
	
	if((midden.offsetHeight - footer.offsetHeight) < viewportheight)
		midden.style.marginTop = parseInt((viewportheight - (midden.offsetHeight - footer.offsetHeight)) / 2) + "px";
	else
		midden.style.marginTop = 0;
	
	afb.style.height = viewportheight+"px";
	afb.style.width = viewportwidth+"px";
}