@import url("https://fonts.googleapis.com/css2?family=DM+Mono:ital,wght@0,300;0,400;0,500;1,300;1,400;1,500&display=swap");
body {
  background-color: rgb(247, 248, 249);
  font-family: "DM Mono", monospace;
}
.wrapper {
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
  max-width: 400px;
  margin: 50px auto;
}
.card {
  width: 100px;
  height: 100px;
  perspective: 1000px;
  cursor: pointer;
  position: relative;
  transform-style: preserve-3d;
  transition: transform 0.6s;
}
.card.flipped {
  transform: rotateY(180deg);
}
.card-front,
.card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
  border: 1px solid #000;
  font-size: 3rem;
  font-weight: 800;
}
.card-front {
  background-color: #fff;
  transform: rotateY(180deg);
}
.card-back {
  background-color: #3498db;
}

#gameOverContainer {
  visibility: hidden;
  opacity: 0;
  background-color: rgba(0, 0, 0, 0.5);
  top: 0;
  left: 0;
}
#gameOverContainer.show {
  visibility: visible;
  opacity: 1;
  transition: opacity 0.7s linear;
}
h2 {
  font-size: 3rem;
}
