function BrowserCheck() {
          var nav = navigator.appName
          if (nav == "Netscape") return 0;
          if (nav == "Microsoft Internet Explorer" || nav=="msie") return 1;
          return 2;
       }

       function getScreenWidth() {
          if (BrowserCheck() == 1) {
             return document.body.offsetWidth
          } else {
             return window.innerWidth
          }
       }

       function getScreenHeight() {
          return (BrowserCheck() == 1) ? document.body.offsetHeight : window.innerHeight ;
       }



       function setTopImage(iw, ih, fh) {
          var w = getScreenWidth();
          if (fh) {
             var h = fh;
          } else {
             var h = Math.floor(w * ih / iw);
          }
          document.images.topPic.height = h
          document.images.topPic.width = w
       }

       function ton($tonDatei) {
         document.getElementById("head_span").innerHTML='< bgsound src="' + $tonDatei + '" loop="1"/>';
         document.getElementById("body_span").innerHTML='< embed src="' + $tonDatei + '" autostart="true" loop="false" hidden="true" height="0" width="0"/> ';
       }