.attachment--preview {
  position: relative;
  width: 100%;
}

.attachment--preview img {
  display: block;
  width: 100%;
  height: auto;
}

.attachment__caption {
  position: absolute;
  inset: auto 0 0;
  z-index: 10;
  padding: 0.75rem 1rem;
  color: #fff;
  background: rgb(0 0 0 / 70%);
  opacity: 0;
  visibility: hidden;
  transition: opacity 0.2s ease, visibility 0.2s ease;
}

.attachment--preview:hover .attachment__caption {
  opacity: 1;
  visibility: visible;
}