details {
  position: relative;
}

details > *,
details .lightbox-wrapper {
  display: none;
}

summary:first-of-type {
  cursor: pointer;
  display: block;
}

summary:before {
  content: '\25BA';
  margin-right: .25em;
}

details[open] > summary:before,
details.open  > summary:before {
  content: '\25BC';
}

details[open] > summary:first-of-type ~ *,
details.open  > summary:first-of-type ~ * {
  display: block;
}

/* hide native indicator */
summary::-webkit-details-marker {
  display: none;
}

/* FF: hide div generated by lazyYT plugin */
details .lazyYT-container {
  display: none;
}