:root {
    --bg: #f4f6f9;
    --card: #ffffff;
    --primary: #2c3e50;
    --accent: #3498db;
    --text: #333;
}

body.dark {
    --bg: #121212;
    --card: #1e1e1e;
    --primary: #000;
    --accent: #4da6ff;
    --text: #fff;
}

body {
    margin: 0;
    font-family: Arial, sans-serif;
    background: var(--bg);
    color: var(--text);
}

header {
    background: var(--primary);
    padding: 1rem;
    color: white;
}

nav a {
    color: white;
    margin-right: 15px;
    text-decoration: none;
}

main {
    padding: 20px;
}

.stats-grid {
    display: grid;
    grid-template-columns: repeat(auto-fit,minmax(200px,1fr));
    gap: 20px;
}

.stat-card {
    background: var(--card);
    padding: 20px;
    border-radius: 10px;
    text-align: center;
    box-shadow: 0 5px 10px rgba(0,0,0,0.1);
}