var varUserAgent = navigator.userAgent;

document.write('<link rel="stylesheet" href="css/style13.css" type="text/css" media="screen, projection" />');
document.write('<link rel="stylesheet" href="css/print_style13.css" type="text/css" media="print" />');

if (varUserAgent.indexOf('Mac') != -1) {
	if (varUserAgent.indexOf('Firefox') != -1) {
			document.write('<link rel="stylesheet" href="css/macfirefox.css" type="text/css" media="screen, print, projection" />');
	}
}