function flip ()
{
	var body = document.getElementsByTagName('body')[0];
	
	if (!body.toggle)
		body.toggle = 3;
	
	if (body.toggle == 1) 
		body.style.backgroundImage = "url('/images/Banner/zitterlings.jpg')";
	else if (body.toggle == 2)
		body.style.backgroundImage = "url('/images/Banner/raden.jpg')";
	else
 	{
		body.style.backgroundImage = "url('/images/Banner/bruecke.jpg')";
		body.toggle = 0;
	}
	

	++body.toggle;
}