function HideIfMac(divid)
{
   if (navigator.userAgent.indexOf("Mac") != -1) {
      document.getElementById(divid).style.display = "none";
   }
}
function HideIfWin(divid)
{
   if (navigator.userAgent.indexOf("Win") != -1) {
      document.getElementById(divid).style.display = "none";
   }
}
function HideIfLinux(divid)
{
   if (navigator.userAgent.indexOf("Linux") != -1) {
      document.getElementById(divid).style.display = "none";
   }
}