.Card {
  display: block;
  position: relative;
  background: black;
}

.Card:hover .Card-background {
  opacity: 0.5;
}

.Card-background {
  transition: all 0.3s ease;
  position: absolute;
  top: 0;
  bottom: 0;
  right: 0;
  left: 0;
}

.Card-background + * {
  position: relative;
}