discourse/app/assets/stylesheets/mobile/lightbox.scss

.lightbox .meta,
.lightbox:hover .meta {
  opacity: 0.7;
}

.meta {
  display: flex;
  align-items: center;
  justify-content: center;
  background: $secondary;
  color: $primary-high;
  height: 25px;
  width: 25px;
  bottom: 0;
  right: 0;

  .filename,
  .informations {
    display: none;
  }

  .expand {
    position: initial;
  }
}