*, *::before, *::after {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
}

body, html {
    background-color: #000022;
    color: #e0e0ff;
    font-family: 'Courier New', monospace;
    min-height: 100vh;
    overflow-x: hidden;
}

.game-header {
    display: flex;
    align-items: center;
    padding: 10px 20px;
    gap: 20px;
}

.game-title {
    font-family: 'Courier New', monospace;
    font-size: clamp(20px, 5vw, 36px);
    color: #00ffff;
    text-shadow:
        0 0 10px #00ffff,
        0 0 20px #00ffff,
        0 0 40px #0088ff;
    letter-spacing: 2px;
}

#gameWrapper {
    max-width: 600px;
    margin: 0 auto;
    padding: 20px;
    display: flex;
    flex-direction: column;
    align-items: center;
}

#scoreBoard {
    text-align: center;
    color: #00ffff;
    font-size: 16px;
    padding: 10px;
    text-shadow:
        0 0 5px rgba(0, 255, 255, 0.5),
        0 0 10px rgba(0, 255, 255, 0.3);
    font-family: 'Courier New', monospace;
    letter-spacing: 1px;
}

#gameGrid {
    display: grid;
    grid-template-columns: repeat(4, 1fr);
    gap: 12px;
    max-width: 500px;
    width: 100%;
    padding: 20px;
}

.card {
    aspect-ratio: 1;
    border-radius: 10px;
    cursor: pointer;
    perspective: 600px;
    position: relative;
}

.card:hover .card-inner {
    filter: brightness(1.2);
}

.card:hover .card-front {
    box-shadow:
        0 0 10px rgba(0, 170, 255, 0.4),
        0 0 20px rgba(0, 170, 255, 0.2);
}

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

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

.card-front {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    background: linear-gradient(135deg, #0a1530, #0d1f45);
    border: 2px solid #00aaff;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 24px;
    color: #00aaff;
    text-shadow: 0 0 8px rgba(0, 170, 255, 0.5);
    transition: box-shadow 0.3s ease;
}

.card-back {
    position: absolute;
    width: 100%;
    height: 100%;
    backface-visibility: hidden;
    transform: rotateY(180deg);
    background: #0a0a2a;
    border: 2px solid #00aaff;
    border-radius: 10px;
    display: flex;
    align-items: center;
    justify-content: center;
    font-size: 42px;
}

.card.matched {
    opacity: 0.6;
    pointer-events: none;
}

.card.matched .card-back {
    border-color: #ffd700;
    box-shadow: 0 0 15px rgba(255, 215, 0, 0.3);
}

.card.matched .card-front {
    border-color: #ffd700;
}

#restartBtn {
    background: transparent;
    border: 2px solid #00aaff;
    color: #00ffff;
    padding: 10px 30px;
    font-family: 'Courier New', monospace;
    font-size: 14px;
    cursor: pointer;
    border-radius: 5px;
    margin-top: 20px;
    transition: all 0.3s ease;
    text-transform: uppercase;
    letter-spacing: 2px;
}

#restartBtn:hover {
    background: rgba(0, 170, 255, 0.2);
    box-shadow:
        0 0 10px rgba(0, 170, 255, 0.4),
        0 0 20px rgba(0, 170, 255, 0.2);
}

footer {
    text-align: center;
    padding: 30px 20px;
    border-top: 1px solid rgba(0, 170, 255, 0.1);
    margin-top: 40px;
    color: #445566;
    font-size: 12px;
}

@media (max-width: 500px) {
    #gameGrid {
        gap: 8px;
        padding: 10px;
    }

    .card-back {
        font-size: 28px;
    }

    .card-front {
        font-size: 18px;
    }

    #scoreBoard {
        font-size: 13px;
    }
}