if(navigator.appName == "Netscape")
  {
   //alert("You're using a Netscape browser.")
   document.getElementById("height30div").className="tabHtNet4";
  }
  else if(navigator.appName == "Opera")
  {
   document.getElementById("height30div").className="tabHtOpera4";
   //alert("You're using a Opera browser.")
  }
  else
  {
   document.getElementById("height30div").className="tabHtIE4";
   //alert("You're using a IE browser.")
  }