:root {
            --primary-color: #8e44ad;
            --secondary-color: #f39c12;
            --accent-color: #27ae60;
            --text-dark: #2c3e50;
            --text-light: #7f8c8d;
            --bg-light: #ecf0f1;
        }
        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: 1px 1px 2px rgba(0,0,0,0.1);
        }
        .hero-section {
            background: linear-gradient(135deg, var(--primary-color), #9b59b6);
            color: white;
            padding: 4rem 0;
            margin-bottom: 2rem;
            border-radius: 0 0 20px 20px;
        }
        .section-title {
            color: var(--primary-color);
            border-left: 5px solid var(--secondary-color);
            padding-left: 15px;
            margin: 2rem 0 1.5rem;
        }
        .content-card {
            background: white;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.05);
            padding: 2rem;
            margin-bottom: 2rem;
            transition: transform 0.3s ease;
        }
        .content-card:hover {
            transform: translateY(-5px);
        }
        .highlight {
            background-color: rgba(243, 156, 18, 0.1);
            border-left: 4px solid var(--secondary-color);
            padding: 1rem;
            margin: 1.5rem 0;
            border-radius: 0 5px 5px 0;
        }
        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary-color);
            margin-bottom: 1rem;
        }
        .img-container {
            border-radius: 10px;
            overflow: hidden;
            margin: 2rem 0;
            box-shadow: 0 10px 20px rgba(0,0,0,0.1);
        }
        .table-of-contents {
            background: white;
            border-radius: 10px;
            padding: 1.5rem;
            margin-bottom: 2rem;
            box-shadow: 0 5px 15px rgba(0,0,0,0.05);
        }
        .toc-item {
            margin-bottom: 0.5rem;
            padding-left: 1rem;
            border-left: 3px solid transparent;
            transition: all 0.3s ease;
        }
        .toc-item:hover {
            border-left-color: var(--primary-color);
            padding-left: 1.5rem;
        }
        .toc-item a {
            text-decoration: none;
            color: var(--text-dark);
        }
        .toc-item a:hover {
            color: var(--primary-color);
        }
        .key-term {
            font-weight: 700;
            color: var(--primary-color);
        }
        footer {
            background-color: var(--text-dark);
            color: white;
            padding: 3rem 0 2rem;
            margin-top: 3rem;
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 2rem 0;
                border-radius: 0 0 15px 15px;
            }
            .content-card {
                padding: 1.5rem;
            }
        }