.card {
  width: 150px;
  height: 150px;
  position: relative;
  perspective: 800px;
  cursor: pointer;
}

.card::before,
.card::after {
  content: "";
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  transition: 0.6s;
  box-shadow: 0.2em 0.2em 0.5em rgba(0, 0, 0, 0.2);
  border-radius: 0.5em;
  z-index: -1;
}

.card::before {
  background: url("../images/default.jpg") center/cover no-repeat;
}

.card::after {
  background: var(--card-img, hsl(0, 0%, 90%, 0.5)) center/cover no-repeat;
  transform: rotateY(180deg);
}

.card.flipped::before {
  transform: rotateY(-180deg);
}

.card.flipped::after {
  transform: rotateY(0);
}