body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  text-align: center;
  background-color: #f4f4f4;
  margin: 0;

}

h1 {
  color: #333;
}

.game-board {
  width: 640px;
  max-width: 90%;
  margin: 20px auto;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 10px;
}


.card {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
  perspective: 1000px;
  cursor: pointer;
}

.card-inner {
  width: 100%;
  height: 100%;
  transition: transform 0.6s;
  transform-style: preserve-3d;
  position: relative;
}

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

.card-front,
.card-back {
  position: absolute;
  width: 100%;
  height: 100%;
  backface-visibility: hidden;
  border-radius: 8px;
}

.card-front {
  background-color: #2c3e50;
}

.card-back {
  background-color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 2rem;
  transform: rotateY(180deg);
  border: 2px solid #2980b9;
}

#mensaje-final {
  font-size: 1.2rem;
  color: green;
  margin-top: 20px;
}