function aktivierenv(DivId, top1, top2)
    {
    document.getElementById(DivId).style.visibility = "visible";
      if (DivId=='DivS1_On') 
      {
      document.getElementById('DivS1_On').style.top=top1+"px";
      document.getElementById('DivS1_Off').style.visibility = "hidden";
      document.getElementById('DivS2_On').style.visibility = "hidden";
      document.getElementById('DivS1_On').style.visibility = "visible";
      document.getElementById('DivS2_Off').style.visibility = "visible";
      } else {
      document.getElementById('DivS1_Off').style.top=top1+"px";
      }
      if (DivId=='DivS2_On') 
      {
      document.getElementById('DivS2_On').style.top=top2+"px";
      document.getElementById('DivS2_Off').style.visibility = "hidden";
      document.getElementById('DivS1_On').style.visibility = "hidden";
      document.getElementById('DivS2_On').style.visibility = "visible";
      document.getElementById('DivS1_Off').style.visibility = "visible";
      } else {
      document.getElementById('DivS2_Off').style.top=top2+"px";
      }
    }