@media only screen and (max-width: 900px) {
  /* 外部 */
  .phone-class {
    width: 100%!important;
    margin: 0 0 10px 0 !important;
  }
  /* 内部 */
  .phone-content {
    width: 96%!important;
    margin: 0 2% 10px!important;
  }
  .footer-top-external{
    height: 0!important;
  }
}

@media only screen and (min-width: 900px) and (max-width: 1280px){
  body{
    width: 1280px!important;
  }
}