NS4 = (document.layers);
     IE4 = (document.all);
     isMac = (navigator.appVersion.indexOf("Mac") != -1);
 
 // NS for Mac
if ((NS4) && (isMac)) {
document.write('<link rel=\"STYLESHEET\" type=\"text/css\" href="stili03.css">');
}
 // IE for Mac
else if ((!NS4) && (isMac)) {
document.write('<link rel=\"STYLESHEET\" type=\"text/css\" href="stili.css">');
}
// NS for Win
else if ((NS4) && (!isMac)) {
document.write('<link rel=\"STYLESHEET\" type=\"text/css\" href="stili02.css">');
}
// IE for Win
else {
document.write('<link rel=\"STYLESHEET\" type=\"text/css\" href="stili.css">');
}