div#panel-unsupported {
  display: none;
  position: relative;
  width: 100%;
  height: 100%;
}

@media only screen and (max-width: 768px) {
  div#main > :not(#panel-unsupported) {
    display: none;
  }
  div#main > div#panel-unsupported {
    display: block;
  }
}