@media only screen and (min-width: 641px) {
  .advert, .responsive-article-ad {
    display: none;
  }
}
@media only screen and (max-width: 640px) {
  .advert, .responsive-article-ad {
    display: block;
  }

  .advert iframe {
    margin: auto;
    display: flex;
  }
}