<!--
if (document.layers){ //Netscape 4.x 
document.write("<link rel='stylesheet' href='stile_netscape4.css' type='text/css'>"); 
} 
else if (document.getElementById){ //Netscape 6.x, Netscape 7.x, Explorer 5 e 6, Opera 5 e 6, Mozilla
document.write("<link rel='stylesheet' href='stile.css' type='text/css'>");
}
//-->