function detectMacXFF() {
  var userAgent = navigator.userAgent.toLowerCase();
  if (userAgent.indexOf('mac') != -1 && userAgent.indexOf('firefox')!=-1) {
    return true;
  }
}
  var d = detectMacXFF(); //note new detectMacXFF2 script above
  if (d) {
  document.write("<style>#ul_mainNav {width:auto; display:block; list-style:none; margin:0; padding:0;} #ul.mainNav li a span {display: block; padding: 9px 12px 9px 12px;}</style>");
 }