MediaWiki:Common.css

/********* [[Template:Spoiler]] *********/
.spoiler-content {
  background-color: var(--main-background-color); /* fallback */
  background-color: color-mix(in srgb, var(--main-background-color) 50%, transparent);
  transition: all 0.3s;
  cursor: pointer;
  overflow:auto;
}

.spoiler-content > * {
  pointer-events:none;
  opacity: 0;
  transition: all 0.3s;
}

.spoiler-content.show {
  background-color: transparent;
}

.spoiler-content.show > * {
  pointer-events:unset;
  opacity: 1;
}