:root {
            --primary-color: #ff6b35;
            --secondary-color: #004e98;
            --accent-color: #ffd166;
            --text-dark: #2d3142;
            --text-light: #f7f7f7;
            --bg-light: #f8f9fa;
        }
        body {
            font-family: 'Segoe UI', system-ui, sans-serif;
            line-height: 1.7;
            color: var(--text-dark);
            background-color: var(--bg-light);
        }
        .navbar-brand {
            font-weight: 800;
            font-size: 1.8rem;
            color: var(--primary-color) !important;
            text-shadow: 1px 1px 2px rgba(0,0,0,0.1);
        }
        .hero-section {
            background: linear-gradient(135deg, var(--secondary-color) 0%, var(--primary-color) 100%);
            color: white;
            padding: 4rem 0;
            margin-bottom: 2rem;
            border-radius: 0 0 20px 20px;
        }
        .content-section {
            background: white;
            border-radius: 15px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.05);
            padding: 2.5rem;
            margin-bottom: 2rem;
        }
        h1, h2, h3 {
            color: var(--secondary-color);
            margin-bottom: 1.5rem;
            font-weight: 700;
        }
        h1 {
            color: white;
            font-size: 2.8rem;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.2);
        }
        h2 {
            border-left: 5px solid var(--primary-color);
            padding-left: 1rem;
            margin-top: 2.5rem;
        }
        h3 {
            color: var(--primary-color);
            margin-top: 2rem;
        }
        .key-term {
            background-color: var(--accent-color);
            padding: 0.2rem 0.5rem;
            border-radius: 4px;
            font-weight: 600;
        }
        .highlight-box {
            background: linear-gradient(135deg, #e9f7ff 0%, #f0f9ff 100%);
            border-left: 4px solid var(--secondary-color);
            padding: 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        .game-feature {
            background: white;
            border-radius: 10px;
            padding: 1.5rem;
            margin: 1rem 0;
            box-shadow: 0 3px 10px rgba(0,0,0,0.08);
            transition: transform 0.3s ease;
        }
        .game-feature:hover {
            transform: translateY(-5px);
        }
        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary-color);
            margin-bottom: 1rem;
        }
        img {
            max-width: 100%;
            height: auto;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
            margin: 1.5rem 0;
        }
        .img-caption {
            text-align: center;
            font-style: italic;
            color: #666;
            margin-top: -0.5rem;
            margin-bottom: 1.5rem;
        }
        .nav-pills .nav-link.active {
            background-color: var(--primary-color);
            font-weight: 600;
        }
        .nav-pills .nav-link {
            color: var(--secondary-color);
        }
        footer {
            background-color: var(--secondary-color);
            color: white;
            padding: 2rem 0;
            margin-top: 3rem;
        }
        .toc {
            position: sticky;
            top: 20px;
            background: white;
            border-radius: 10px;
            padding: 1.5rem;
            box-shadow: 0 3px 10px rgba(0,0,0,0.08);
        }
        .toc ul {
            padding-left: 1.2rem;
        }
        .toc li {
            margin-bottom: 0.5rem;
        }
        .toc a {
            color: var(--secondary-color);
            text-decoration: none;
            transition: color 0.3s;
        }
        .toc a:hover {
            color: var(--primary-color);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 2.5rem 0;
            }
            h1 {
                font-size: 2.2rem;
            }
            .content-section {
                padding: 1.5rem;
            }
        }