var acn = navigator.appCodeName;
  var an = navigator.appName;
  var av = navigator.appVersion;
  var ua = navigator.userAgent;

  var docAll = document.all;
  var docComment = document.createComment;
  var docLayers = document.layers;
  var docById = document.getElementById;
  var docFire = document.fireEvent;
  var op = (window.opera);

  var ieAN = navigator.appName.indexOf("Explorer");
  var nsAN = navigator.appName.indexOf("Netscape");
  var opAN = navigator.appName.indexOf("Opera");

  var ieAV = navigator.appVersion.indexOf("MSIE")
  var ie7AV = navigator.appVersion.indexOf("7.0");

  var ieUA = navigator.userAgent.indexOf("MSIE");
  var ie7UA = navigator.userAgent.indexOf("7.0");
  var ie6UA = navigator.userAgent.indexOf("6.0");

  var ffUA = navigator.userAgent.indexOf("Firefox");
  var nsUA = navigator.userAgent.indexOf("Netscape");
  var opUA = navigator.userAgent.indexOf("Opera");


  //IE7
  var ie7 = (docAll && docFire && (ieAV != -1) && (ie7AV != -1) && (ieUA != -1) && (ie7UA != -1) && !op);
  if(ie7)
  {
    document.writeln("<link rel=\"stylesheet\" type=\"text/css\" href=\"ie7.css\">");
  }

  //IE6
  var ie6 = (docAll && docFire && (ieAV != -1) && (ieUA != -1) && (ie6UA != -1) && !op && (ie7UA == -1));
  if(ie6)
  {
    document.writeln("<link rel=\"stylesheet\" type=\"text/css\" href=\"ie6.css\" / >");
  }

  //Firefox 
  var firefox = (!docAll && !docFire && docById && (ffUA != -1));
  if(firefox)
  {
    document.writeln("<link rel=\"stylesheet\" type=\"text/css\" href=\"ff.css\" / >");
  }

  //Netscape
  var ns = (!docAll && !docFire && docById && (nsUA != -1));
  if(ns)
  {
    document.writeln("<link rel=\"stylesheet\" type=\"text/css\" href=\"ns.css\" / >");
  }	

  //Opera
  var op  = (docAll && !docFire && (opUA != -1) && op);
  if(op)
  {
    document.writeln("<link rel=\"stylesheet\" type=\"text/css\" href=\"op.css\" / >");
  }