Great effect, looks nice :D

its very Good Sir :)

One advice, you should rather do the hover detection on parent card, like that you'll not have a weird effect when slowly moving mouse from left or right for example.
Instead of

.card:hover {
  transform: rotateY(180deg);
}

It would be better to set

.card-container:hover .card {
  transform: rotateY(180deg);
}