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

        body {
            background-color: #1a1a1a;
            color: #e0e0e0;
            font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, Oxygen, Ubuntu, Cantarell, sans-serif;
            min-height: 100vh;
            display: flex;
            flex-direction: column;
        }

        header {
            padding: 1.5rem 2rem;
            border-bottom: 1px solid #2a2a2a;
            display: flex;
            justify-content: space-between;
            align-items: center;
        }

        h1 {
            font-size: 1.5rem;
            font-weight: 300;
            letter-spacing: 1px;
        }

        .back-btn {
            background: none;
            border: 1px solid #333;
            color: #e0e0e0;
            padding: 0.5rem 1rem;
            cursor: pointer;
            border-radius: 4px;
            transition: all 0.3s ease;
            font-size: 0.9rem;
        }

        .back-btn:hover {
            background-color: #242424;
            border-color: #444;
        }

        main {
            flex: 1;
            display: flex;
            justify-content: center;
            align-items: center;
            padding: 2rem;
        }

        .game-box {
            width: 100%;
            max-width: 1200px;
            height: 600px;
            aspect-ratio: 1;
            border: 1px solid #333;
            background-color: #242424;
            border-radius: 4px;
        }