// varsion check //
var Win=(navigator.userAgent.indexOf("Win")!=-1);
var Mac=(navigator.userAgent.indexOf("Mac")!=-1);
var Explorer=(navigator.appName.indexOf("Explorer")!=-1);
var Netscape=(navigator.appName.indexOf("Netscape")!=-1);

if
(Win && Explorer)
{document.write('<LINK rel="stylesheet" href="css/win_ie.css" type="text/css">');}

else if
(Win && Netscape) 
{document.write('<LINK rel="stylesheet" href="css/win_nn.css" type="text/css">');}

else if
(Mac && Explorer) 
{document.write('<LINK rel="stylesheet" href="css/mac_ie.css" type="text/css">');}

else if
(Mac && Netscape) 
{document.write('<LINK rel="stylesheet" href="css/mac_nn.css" type="text/css">');}