function openImpressum(){
	pop_width = 535; left_pos = (screen.availWidth - pop_width) / 2; 
 		pop_height = 400; top_pos = (screen.availHeight - pop_height) / 2; 
	properties = 'location=no,menubar=no,resizable=no,scrollbars=yes,status=no,toolbar=no';
	myURL = "impressum-2.html";
	imp=window.open(myURL,'bravohits',''+properties+',width='+pop_width+',height='+pop_height+',left='+left_pos+',top='+top_pos+'');
		imp.focus();
}