function browser() {

  var agent = navigator.userAgent ;
  var appve = navigator.appVersion ;
  var appna = navigator.appName ;
  var userOs = null ;
  var browser = null ;
  var version = null ;


  if(agent.indexOf('Win') != -1 ){
    userOs = "Win";
  }
  else if( agent.indexOf('Mac') != -1 ){
    userOs = "Mac" ;
  }
  else{
    userOs = "other" ;
  }

  if ( appna == "Microsoft Internet Explorer" ){
    browser = "MSIE";
    version = agent.substring((agent.indexOf('MSIE') + 5),(agent.indexOf('MSIE') + 8)) ;
  }
  else if ( appna == "Netscape" ){
   browser = "NN";
   version = appve.substring( 0,3 ) ;
  }


  var macUrl, winUrl, cssSrc ;


  win_IE_Url = "/lc/css/common_w_i.css";
  win_NN_Url = "/lc/css/common_w_n.css";
  mac_IE_Url = "/lc/css/common_m_i.css";
  mac_NN_Url = "/lc/css/common_m_n.css";


  if (userOs == "Win" && browser == "MSIE") {

   cssSrc = '<link rel="stylesheet" type="text/css" href="' + win_IE_Url + '">' ;
  }
  else if (userOs == "Win" && browser == "NN") {

   cssSrc = '<link rel="stylesheet" type="text/css" href="' + win_NN_Url + '">' ;
  }
  else if (userOs == "Mac" && browser == "MSIE") {

   cssSrc = '<link rel="stylesheet" type="text/css" href="' + mac_IE_Url + '">' ;
  }
  else if (userOs == "Mac" && browser == "NN") {

   cssSrc = '<link rel="stylesheet" type="text/css" href="' + mac_NN_Url + '">' ;
  } else {

   cssSrc = '<link rel="stylesheet" type="text/css" href="' + win_IE_Url + '">' ;
  }

  document.write( cssSrc ) ; 
}

browser();