usrAg = navigator.userAgent.toLowerCase();
appN = navigator.appName.toLowerCase();
ieForMac = (usrAg.indexOf("mac")!=-1 && appN.indexOf("explorer")!=-1) ? true : false;
if (ieForMac) {/*alert("Stai usando Explorer per Mac!");*/ document.write('<link rel="STYLESHEET" type="text/css" media="screen" href="lib/screen_iemac.css"/>');}