#contents {
  width: 800px;
  margin: auto;
  padding: 72px 0 2.5rem 0!important;
}

#mailaddress_area p {
  display: none;
}

@media screen and (max-width: 991.98px) {
  #contents {
    width: 90%!important;
  }

  #gamen_name {
    margin-top: 1rem!important;
    margin-bottom: 1rem!important;
  }

  #mailaddress_area table {
    display: none;
  }

  #mailaddress_area p {
    display: block;
  }

  #mailaddress_area p:first-child {
    text-decoration: underline;
  }
}