:root {
    --primary-color: #4CAF50;
    --bg-color: #f4f4f9;
    --card-bg: #fff;
    --card-back: #2196F3;
    --text-color: #333;
}

* {
    box-sizing: border-box;
    margin: 0;
    padding: 0;
    font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
}

body {
    background-color: var(--bg-color);
    color: var(--text-color);
    display: flex;
    flex-direction: column;
    align-items: center;
    min-height: 100vh;
}

header {
    text-align: center;
    margin: 20px 0;
}

h1 {
    color: var(--primary-color);
    margin-bottom: 15px;
}

.stats {
    display: flex;
    justify-content: center;
    gap: 30px;
    font-size: 1.2rem;
    font-weight: bold;
}

.stat-box {
    background: white;
    padding: 10px 20px;
    border-radius: 8px;
    box-shadow: 0 4px 6px rgba(0,0,0,0.1);
}

main {
    flex: 1;
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
    padding: 20px;
}

.game-board {
    display: grid;
    gap: 15px;
    /* Grid columns will be set by JS dynamically based on level */
    justify-content: center;
}

/* Card Styling and Flip Animation */
.card {
    width: 80px;
    height: 80px;
    perspective: 1000px; /* Gives 3D effect */
    cursor: pointer;
}

.card-inner {
    width: 100%;
    height: 100%;
    position: relative;
    transition: transform 0.6s;
    transform-style: preserve-3d;
}

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

.card-front, .card-back {
    width: 100%;
    height: 100%;
    position: absolute;
    backface-visibility: hidden;
    display: flex;
    justify-content: center;
    align-items: center;
    font-size: 2rem;
    font-weight: bold;
    border-radius: 8px;
    box-shadow: 0 4px 8px rgba(0,0,0,0.1);
}

.card-front {
    background-color: var(--card-back);
    color: transparent;
    /* You could put a logo or pattern here */
    background-image: repeating-linear-gradient(
        45deg,
        rgba(255, 255, 255, 0.2) 25%,
        transparent 25%,
        transparent 50%,
        rgba(255, 255, 255, 0.2) 50%,
        rgba(255, 255, 255, 0.2) 75%,
        transparent 75%,
        transparent
    );
    background-size: 20px 20px;
}

.card-back {
    background-color: var(--card-bg);
    color: var(--text-color);
    transform: rotateY(180deg);
    border: 2px solid var(--primary-color);
}

.card.matched .card-back {
    background-color: #d4edda;
    border-color: #28a745;
    color: #155724;
}

footer {
    margin-top: auto;
    padding: 20px;
    text-align: center;
    font-weight: bold;
    color: #666;
}