browser = navigator.appName;
    ie = "Microsoft Internet Explorer";
    netscape = "Netscape";
    os = navigator.platform;
    mac = 'Mac_PowerPC'

    if (browser == netscape && os != mac) {
        document.write('<link rel="stylesheet" type="text/css" href="http://www.apha.com/aphacss/pcnn.css" title="pcnn master">');
        }
    else if (browser == ie && os != mac) {
        document.write('<link rel="stylesheet" type="text/css" href="http://www.apha.com/aphacss/pcie.css" title="pcie master">');
        }
    else if (browser == netscape && os == mac) {
        document.write('<link rel="stylesheet" type="text/css" href="http://www.apha.com/aphacss/macnn.css" title="macnn master">');
        }
    else if (browser == ie && os == mac) {
        document.write('<link rel="stylesheet" type="text/css" href="http://www.apha.com/aphacss/macie.css" title="macie master">');
        }
    else  {
        document.write('<link rel="stylesheet" type="text/css" href="http://www.apha.com/aphacss/pcie.css" title="pcie master">');
        }