var Win   = navigator.userAgent.indexOf("Win") != -1 ? true : false 
    var Mac   = navigator.userAgent.indexOf("Mac") != -1 ? true : false 
  
  if (document.getElementById) {

    if (Win)     cssurl = "/am/am-common/css/font.css" // Win
    else if(Mac) cssurl = "/am/am-common/css/font_mac.css" // Mac
  }

  document.write('<link rel="stylesheet" type="text/css" href="'+cssurl+'">')