@media screen and (min-width: 768px) {
  .smallDevices {
    display: none;
  }
  .bigDevices {
    width: 100%;
  }
}
@media screen and (max-width: 767px) {
  .bigDevices {
    display: none;
  }
  .smallDevices {
    width: 100%;
  }
}
iframe {
  border: none;
}