if (is_ie == true) {
      document.write("<link type='text/css' rel='stylesheet' href='css/ie.css'>");
} else if (is_moz_ver == 3) {
      document.write("<link type='text/css' rel='stylesheet' href='css/ff3.css'>");
} else if (is_moz_ver == 2) {
      document.write("<link type='text/css' rel='stylesheet' href='css/ff2.css'>");
} else if (is_opera == true) {
      document.write("<link type='text/css' rel='stylesheet' href='css/opera.css'>");
} else {
      document.write("<link type='text/css' rel='stylesheet' href='css/safari.css'>");
};