function bg(){
	
	var c = ['a','b','c'];
    document.getElementById('kopf').className = c[Math.round(Math.random()*c.length)];
 
   document.getElementById('kopf').className = c[Math.round(Math.random()*c.length)]+" header";
   
}



function oeffner(url) { 	
	fenster1=open(url,"fenster1","width=850,height=600,screenX=320,screenY=0,scrollbars=yes");
	fenster1.focus();
}