body {
    background: black;
    color: white;
    text-align: center;
    font-family: Arial, sans-serif;
}

#game-board {
    width: 90%;
    margin: 20px auto;
    display: grid;
    grid-template-columns: repeat(4, 1fr); /* 🔥 4 columnas */
    gap: 12px;
}

/* 🔥 Cartas grandes y cuadradas */
.card {
    width: 100%;
    aspect-ratio: 1 / 1; /* cuadradas, no se deforman */
    perspective: 1000px;
}

.card-inner {
    width: 100%;
    height: 100%;
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.5s;
}

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

.card-front, .card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 12px;
}

.card-front {
    background: #444;
}

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

/* 🔥 Imágenes perfectas, sin estirarse */
.card-back img {
    width: 100%;
    height: 100%;
    object-fit: cover; /* mantiene proporción */
    border-radius: 12px;
}

.hidden {
    display: none;
}