//function calcheight() {

var height;
if (self.innerHeight) // all except Explorer
{
	height = self.innerHeight;
}
else if (document.documentElement && document.documentElement.clientHeight)
	// Explorer 6 Strict Mode
{
	height = document.documentElement.clientHeight;
}
else if (document.body) // other Explorers
{
	height = document.body.clientHeight;
}

var restheight = eval(height - 648);
var halfheight = eval(restheight / 2);

document.getElementById("oben").style.height = halfheight+"px";
document.getElementById("bottom").style.height = halfheight+"px";

//}

//window.onload = calcheight();