function check_height(){
         var height = window.innerHeight || (window.document.documentElement.clientHeight || window.document.body.clientHeight);
         height -= 240;

         var soll = 0;

         var box01_height = document.getElementById("content_left").offsetHeight;
         var box02_height = document.getElementById('content_right').offsetHeight;

         //alert(box02_height);

         if(box01_height > soll){soll = box01_height;}
         if(box02_height > soll){soll = box02_height;}

         //alert("Soll: "+soll+" / Hoehe: "+height);

         document.getElementById('content_left').style.height = height+"px";
         document.getElementById('content_right').style.height = height+"px";
         document.getElementById('content').style.height = height+"px";

         /*
         if(soll<height){

         }
         else{
                 document.getElementById('content').style.height = soll+"px";
         }
         */
}