var browserName=navigator.appName;
var browserVer=parseInt(navigator.appVersion);
if ((browserName=="Netscape" && browserVer>=5) || (browserName=="Microsoft Internet Explorer" && browserVer>=4))
  version="n3";
else
  version="n2";

if (version=="n3")
  document.write("<link rel='stylesheet' type='text/css' href='style.css' title='style'>");
else
  document.write("<link rel='stylesheet' type='text/css' href='stylenn.css' title='stylenn'>");