style.css

* {
  box-sizing: border-box;
}

body {
  padding: 0;
  margin: 0;
  background: rgb(42, 43, 53);
}

.main-header {
  font-family: Arial, Helvetica, sans-serif;
  font-size: 45px;
  font-weight: bold;
  color: rgb(240, 240, 240);
  text-align: center;
  padding: 10px;
}

.exp-container {
  text-align: center;
  background: white;
  padding: 10px;
}

.exp-header {
  font-size: 30px;
}

.game-container {
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  flex-direction: column;
}

.cards-container {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(3, 1fr);
  grid-gap: 15px;
}

.card {
  width: 130px;
  height: 170px;
  /* box-shadow: 0 0 10px rgba(29, 24, 24, 0.39); */
  background-color: transparent;
  position: relative;
  text-align: center;
  transition: transform 0.3s;
  transform-style: preserve-3d;
}

.card-img {
  width: 130px;
  height: 170px;
}

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

.card-front, .card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
}

.card-front {
  background-image: url(./resources/gf-cardback.jpg);
  background-size: 100%;
  color: black;
}

.card-back {
  color: white;
  transform: rotateY(180deg);
}

.hidden {
  opacity: 0;
  transition: opacity 0.7s;
}