body {
    font-family: Arial, sans-serif;
    background-color: #f0f0f0;
    margin: 0;
    padding: 0;
    display: flex;
    justify-content: center;
    align-items: center;
    height: 100vh;
    flex-direction: column;
}

.container {
    text-align: center;
}

h1 {
    color: blue;
    font-size: 24px;
    margin-bottom: 20px;
}

#game-board {
    display: grid;
    grid-template-columns: repeat(5, 150px);
    grid-gap: 10px;
    margin-bottom: 20px;
}

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

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

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

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

.card-back {
    background-image: url('img20/bj20.jpg');
    background-size: cover;
}

.card-front {
    background-size: cover;
    transform: rotateY(180deg);
}

#hint-overlay {
    display: none;
    position: fixed;
    top: 0;
    left: 0;
    width: 100%;
    height: 100%;
    background-color: rgba(0, 0, 0, 0.8);
    justify-content: center;
    align-items: center;
}

#hint-overlay img {
    max-width: 90%;
    max-height: 90%;
}

#timer {
    font-size: 20px;
    margin-bottom: 10px;
}

#result {
    font-size: 24px;
    color: red;
    margin-top: 20px;
}

button {
    padding: 10px 20px;
    font-size: 16px;
    cursor: pointer;
    margin-bottom: 20px;
}