:root {
    --bg-color: #f0f8ff;
    --card-bg: #add8e6;
    --card-back: #4a90e2;
    --text-color: #333;
    --accent-color: #ff6b6b;
    --font-family: 'Fredoka One', cursive;
}

body {
    font-family: sans-serif;
    background-color: var(--bg-color);
    margin: 0;
    padding: 20px;
    display: flex;
    justify-content: center;
    align-items: center;
    min-height: 100vh;
    text-align: center;
}

main {
    width: 100%;
    max-width: 600px;
}

h1 {
    font-family: var(--font-family);
    color: var(--text-color);
    font-size: 2.5rem;
    margin-bottom: 10px;
}

.game-info {
    font-size: 1.2rem;
    margin-bottom: 20px;
}

.game-board {
    display: grid;
    grid-template-columns: repeat(5, 1fr);
    gap: 10px;
    perspective: 1000px; /* For 3D effect */
}

.card {
    width: 100%;
    aspect-ratio: 1 / 1; /* Makes the card a square */
    position: relative;
    transform-style: preserve-3d;
    transition: transform 0.6s;
    cursor: pointer;
    border-radius: 10px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

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

.card-face {
    position: absolute;
    width: 100%;
    height: 100%;
    -webkit-backface-visibility: hidden;
    backface-visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    border-radius: 10px;
    font-size: 2.5rem;
}

.card-face.card-front {
    background-color: var(--card-bg);
    color: var(--text-color);
    transform: rotateY(180deg);
}

.card-face.card-back {
    background: var(--card-back);
    background-image: linear-gradient(45deg, #ffffff44 25%, transparent 25%, transparent 75%, #ffffff44 75%, #ffffff44), 
                      linear-gradient(45deg, #ffffff44 25%, transparent 25%, transparent 75%, #ffffff44 75%, #ffffff44);
    background-size: 20px 20px;
    background-position: 0 0, 10px 10px;
}


.restart-btn {
    margin-top: 20px;
    padding: 15px 30px;
    font-family: var(--font-family);
    font-size: 1.2rem;
    border: none;
    border-radius: 10px;
    background-color: var(--accent-color);
    color: white;
    cursor: pointer;
    transition: background-color 0.3s;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.restart-btn:hover {
    background-color: #ff4757;
}

/* For smaller screens */
@media (max-width: 640px) {
    .card-face {
        font-size: 2rem;
    }
    h1 {
        font-size: 2rem;
    }
    .game-board {
        grid-template-columns: repeat(4, 1fr);
    }
}