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);
var Version=navigator.appVersion.charAt(0);

if
(Win && Explorer && Version=="4")
{document.write('<LINK rel="stylesheet" href="css/win_ie5.css" type="text/css">');}

else if
(Win && Netscape && Version=="5")
{document.write('<LINK rel="stylesheet" href="css/win_nn6.css" type="text/css">');}

else if
(Win && Netscape && Version=="4")
{document.write('<LINK rel="stylesheet" href="css/win_nn4.css" type="text/css">');}

else if
(Explorer && Mac && Version=="4") 
{document.write('<LINK rel="stylesheet" href="css/mac_ie5.css" type="text/css">');}

else if
(Mac && Netscape && Version=="5")
{document.write('<LINK rel="stylesheet" href="css/mac_nn6.css" type="text/css">');}

else if
(Mac && Netscape && Version=="4")
{document.write('<LINK rel="stylesheet" href="css/mac_nn4.css" type="text/css">');}

else
{document.write('<LINK rel="stylesheet" href="css/other.css" type="text/css">');}

<!--
function MM_reloadPage(init) {  //reloads the window if Nav4 resized
  if (init==true) with (navigator) {if ((appName=="Netscape")&&(parseInt(appVersion)==4)) {
    document.MM_pgW=innerWidth; document.MM_pgH=innerHeight; onresize=MM_reloadPage; }}
  else if (innerWidth!=document.MM_pgW || innerHeight!=document.MM_pgH) location.reload();
}
MM_reloadPage(true);
//-->