:root {
            --primary-color: #ff6b35;
            --secondary-color: #1a237e;
            --accent-color: #ffd54f;
            --text-dark: #2c3e50;
            --text-light: #f8f9fa;
            --bg-gradient: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.7;
            color: var(--text-dark);
            background-color: #f8f9fa;
        }
        .navbar-brand {
            font-weight: 800;
            font-size: 1.8rem;
            color: var(--primary-color) !important;
            text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
        }
        .hero-section {
            background: var(--bg-gradient);
            color: white;
            padding: 4rem 0;
            margin-bottom: 2rem;
            border-radius: 0 0 20px 20px;
        }
        .content-section {
            background: white;
            border-radius: 15px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.1);
            padding: 2.5rem;
            margin-bottom: 2rem;
        }
        h1, h2, h3 {
            color: var(--secondary-color);
            margin-bottom: 1.5rem;
            font-weight: 700;
        }
        h1 {
            font-size: 2.5rem;
            text-align: center;
            margin-bottom: 2rem;
            color: white;
        }
        h2 {
            font-size: 1.8rem;
            border-left: 5px solid var(--primary-color);
            padding-left: 1rem;
            margin-top: 2.5rem;
        }
        h3 {
            font-size: 1.4rem;
            color: var(--primary-color);
            margin-top: 1.8rem;
        }
        p {
            margin-bottom: 1.5rem;
            text-align: justify;
        }
        .highlight {
            background-color: rgba(255, 107, 53, 0.1);
            border-left: 4px solid var(--primary-color);
            padding: 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        .feature-icon {
            color: var(--primary-color);
            margin-right: 10px;
            font-size: 1.2rem;
        }
        .img-container {
            text-align: center;
            margin: 2rem 0;
        }
        .img-fluid {
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.1);
            max-width: 100%;
            height: auto;
        }
        .caption {
            font-style: italic;
            color: #6c757d;
            margin-top: 0.5rem;
            font-size: 0.9rem;
        }
        .table-of-contents {
            background-color: #f8f9fa;
            border-radius: 10px;
            padding: 1.5rem;
            margin-bottom: 2rem;
        }
        .toc-list {
            list-style-type: none;
            padding-left: 0;
        }
        .toc-list li {
            margin-bottom: 0.8rem;
        }
        .toc-list a {
            color: var(--secondary-color);
            text-decoration: none;
            transition: color 0.3s;
        }
        .toc-list a:hover {
            color: var(--primary-color);
        }
        .footer {
            background-color: var(--secondary-color);
            color: white;
            padding: 2rem 0;
            margin-top: 3rem;
            text-align: center;
        }
        .key-term {
            font-weight: 700;
            color: var(--primary-color);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 2rem 0;
            }
            h1 {
                font-size: 2rem;
            }
            h2 {
                font-size: 1.5rem;
            }
            .content-section {
                padding: 1.5rem;
            }
        }
        .nav-link {
            color: var(--text-dark) !important;
            font-weight: 500;
            transition: color 0.3s;
        }
        .nav-link:hover {
            color: var(--primary-color) !important;
        }
        .navbar-toggler {
            border-color: var(--primary-color);
        }
        .navbar-toggler-icon {
            background-image: url("data:image/svg+xml,%3csvg xmlns='http://www.w3.org/2000/svg' viewBox='0 0 30 30'%3e%3cpath stroke='rgba%28255, 107, 53, 1%29' stroke-linecap='round' stroke-miterlimit='10' stroke-width='2' d='M4 7h22M4 15h22M4 23h22'/%3e%3c/svg%3e");
        }