body {
    font-family: Arial, sans-serif;
    text-align: center;
    background: #f4f6f8;
    margin: 0;
    padding: 0;
}

.board {
    display: grid;
    grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
    gap: 25px;
    justify-content: center;
    margin-top: 20px;
}

/*.board {
    display: grid;
    grid-template-columns: repeat(6, 150px);
    gap: 25px;
    justify-content: center;
    margin-top: 20px;
}*/

.card {
    width: 150px;
    height: 150px;
    perspective: 1000px;
    cursor: pointer;
}

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

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

.card-front, .card-back {
    backface-visibility: hidden;
    width: 100%;
    height: 100%;
    position: absolute;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.card-front {
    background: #2c3e50;
    color: white;
    font-size: 2rem;
    display: flex;
    align-items: center;
    justify-content: center;
}

.card-back {
    background: white;
    transform: rotateY(180deg);
    display: flex;
    align-items: center;
    justify-content: center;
}

.card-back img {
    width: 100%;
    height: 100%;
    /*object-fit: contain;*/
    object-fit: contain;
}

.card.matched {
    opacity: 0.8;
    pointer-events: none;
    /*background-color: #28a745;*/
}