function Is() {
    var agent = navigator.userAgent.toLowerCase();
    this.major = parseInt(navigator.appVersion);
    this.minor = parseFloat(navigator.appVersion);
    this.ns  = ((agent.indexOf('mozilla')!=-1) && ((agent.indexOf('spoofer')==-1) && (agent.indexOf('compatible') == -1)));
    this.ns2 = (this.ns && (this.major == 2));
    this.ns3 = (this.ns && (this.major == 3));
    this.ns4b = (this.ns && (this.major == 4) && (this.minor <= 4.03));
    this.ns4 = (this.ns && (this.major >= 4));
    this.ie   = (agent.indexOf("msie") != -1);
    this.ie3  = (this.ie && (this.major == 2));
    this.ie4  = (this.ie && (this.major >= 4));
    this.op3 = (agent.indexOf("opera") != -1);
    this.win   = (agent.indexOf("win")!=-1);
    this.mac   = (agent.indexOf("mac")!=-1);
    this.unix  = (agent.indexOf("x11")!=-1);	
}

var is = new Is()

if (is.ns) {
	if (is.mac)  {
		document.write('<LINK REL=stylesheet TYPE="text/css" HREF="css/mac_ns.css" TITLE="style">');
		} 
	else {
		document.write('<LINK REL=stylesheet TYPE="text/css" HREF="css/pc_ns.css" TITLE="style">');
		}
}
	
if (is.ie) {
	if (is.mac)  {
		document.write('<LINK REL=stylesheet TYPE="text/css" HREF="css/mac_ie.css" TITLE="style">');
		} 
	else {
		document.write('<LINK REL=stylesheet TYPE="text/css" HREF="css/pc_ie.css" TITLE="style">');
		}
}