/* convert all characters to lowercase to simplify testing */
var _agt = navigator.userAgent.toLowerCase();

/* platform */
var _win = (_agt.indexOf('win') != -1);  // Windows
var _mac = (_agt.indexOf('mac') != -1);  // Macintosh

/* sniffer user agent */
var _ng = (!document.getElementById);
// Netscape 6.x (Gecko)
var _ie = (!document.all);
// Internet Explorer 4.x
var _ns = (!document.layers);
// Netscape 4.x

/* css divergence for several env */
if (_win) { //Windows
        if (_ng) { // Netscape 4
              with (document) {
                      open();
                      writeln('<style type="text/css">');
                      writeln('@import url(../../css/win_ns.css);');
                      writeln('</style>');
                      close();
               }
        }
        else if (_ie) { // Netscape 6.x (Gecko)
              with (document) {
                      open();
                      writeln('<style type="text/css">');
                      writeln('@import url(../../css/win_ng.css);');
                      writeln('</style>');
                      close();
               }
        }
        else if (_ns) { // Internet Explorer 4.x
              with (document) {
                      open();
                      writeln('<link rel="stylesheet" type="text/css"href="../../css/win_ie.css">');
                         close();
               }
        }
}
else if (_mac) { // Macintosh
        if (_ng) { // Netscape 4.x
              with (document) {
                      open();
                      writeln('<style type="text/css">');
                      writeln('@import url(../../css/mac_ns.css);');
                      writeln('</style>');
                      close();
               }
        }
        else if (_ie) { // Netscape 6.x (Gecko)
              with (document) {
                      open();
                      writeln('<style type="text/css">');
                      writeln('@import url(../../css/mac_ng.css);');
                      writeln('</style>');
                      close();
               }
        }
                else if (_ns) { // Internet Explorer 4.x/
              with (document) {
                      open();
                      writeln('<link rel="stylesheet" type="text/css" href="../../css/mac_ie.css">');
                         close();
               }
        }
}