.card-container {
  perspective: 1000px;
}
.card-container:hover .card {
  transform: rotateY(180deg);
}
.card-container, .front, .back {
  width: 200px;
  height: 200px;
}
.front, .back {
  background: #efe;
}
.card {
  transition: 0.6s;
  transform-style: preserve-3d;
  position: relative;
}
.front, .back {
  backface-visibility: hidden;
  position: absolute;
  top: 0;
  left: 0;
}
.front {
  z-index: 2;
  transform: rotateY(0deg);
}

.back {
  transform: rotateY(180deg);
}