#game-container {
    width: 400px;
    height: 500px;
    background-color: #27ae60;
    display: flex;
    justify-content: center;
    align-items: center;
}

#board {
    width: 320px;
    height: 400px;
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    grid-template-rows: repeat(4, 1fr);
    gap: 10px;
}

.card {
    position: relative;
    width: 100%;
    height: 100%;
    transform-style: preserve-3d;
    transition: transform 0.3s;
    cursor: pointer;
}

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

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    border-radius: 8px;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 32px;
}

.card-front {
    background-color: #ecf0f1;
    transform: rotateY(180deg);
}

.card-back {
    background-color: #2c3e50;
    border: 2px solid #34495e;
}

#hud-score {
    position: absolute;
    top: 10px;
    left: 10px;
    background: rgba(0,0,0,0.5);
    padding: 5px 10px;
    border-radius: 5px;
}