:root {
            --primary-color: #ff6b35;
            --secondary-color: #1a237e;
            --accent-color: #ffd54f;
            --text-dark: #2c3e50;
            --text-light: #f8f9fa;
            --bg-light: #f8f9fa;
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, 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: 2px 2px 4px rgba(0,0,0,0.1);
        }
        .nav-link {
            font-weight: 600;
            transition: all 0.3s ease;
        }
        .nav-link:hover {
            color: var(--primary-color) !important;
            transform: translateY(-2px);
        }
        .hero-section {
            background: linear-gradient(135deg, var(--secondary-color) 0%, var(--primary-color) 100%);
            color: white;
            padding: 5rem 0;
            margin-bottom: 3rem;
            border-radius: 0 0 30px 30px;
        }
        .section-title {
            position: relative;
            padding-bottom: 15px;
            margin-bottom: 30px;
            color: var(--secondary-color);
            font-weight: 700;
        }
        .section-title:after {
            content: '';
            position: absolute;
            bottom: 0;
            left: 0;
            width: 80px;
            height: 4px;
            background: var(--primary-color);
            border-radius: 2px;
        }
        .card {
            border: none;
            border-radius: 15px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.08);
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            margin-bottom: 25px;
            overflow: hidden;
        }
        .card:hover {
            transform: translateY(-10px);
            box-shadow: 0 15px 40px rgba(0,0,0,0.15);
        }
        .card-header {
            background: linear-gradient(to right, var(--secondary-color), var(--primary-color));
            color: white;
            font-weight: 700;
            border: none;
            padding: 15px 20px;
        }
        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary-color);
            margin-bottom: 15px;
        }
        .img-fluid {
            border-radius: 15px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.1);
            transition: transform 0.3s ease;
        }
        .img-fluid:hover {
            transform: scale(1.02);
        }
        .highlight {
            background-color: rgba(255, 214, 79, 0.2);
            border-left: 4px solid var(--accent-color);
            padding: 15px 20px;
            margin: 20px 0;
            border-radius: 0 10px 10px 0;
        }
        .btn-primary {
            background: linear-gradient(to right, var(--primary-color), #ff8c42);
            border: none;
            border-radius: 50px;
            padding: 12px 30px;
            font-weight: 600;
            transition: all 0.3s ease;
        }
        .btn-primary:hover {
            transform: translateY(-3px);
            box-shadow: 0 10px 20px rgba(255, 107, 53, 0.3);
        }
        footer {
            background-color: var(--secondary-color);
            color: white;
            padding: 3rem 0 1.5rem;
            margin-top: 4rem;
        }
        .back-to-top {
            position: fixed;
            bottom: 30px;
            right: 30px;
            background: var(--primary-color);
            color: white;
            width: 50px;
            height: 50px;
            border-radius: 50%;
            display: flex;
            align-items: center;
            justify-content: center;
            text-decoration: none;
            box-shadow: 0 5px 15px rgba(0,0,0,0.2);
            transition: all 0.3s ease;
            z-index: 1000;
        }
        .back-to-top:hover {
            transform: translateY(-5px);
            color: white;
        }
        .content-section {
            padding: 40px 0;
        }
        .content-section:nth-child(even) {
            background-color: white;
        }
        .table-of-contents {
            background-color: white;
            border-radius: 15px;
            padding: 25px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.08);
            margin-bottom: 30px;
            position: sticky;
            top: 20px;
        }
        .toc-list {
            list-style-type: none;
            padding-left: 0;
        }
        .toc-list li {
            margin-bottom: 10px;
            padding-bottom: 10px;
            border-bottom: 1px solid #eee;
        }
        .toc-list li:last-child {
            border-bottom: none;
        }
        .toc-list a {
            color: var(--text-dark);
            text-decoration: none;
            transition: all 0.3s ease;
            display: flex;
            align-items: center;
        }
        .toc-list a:hover {
            color: var(--primary-color);
            padding-left: 10px;
        }
        .toc-list a i {
            margin-right: 10px;
            color: var(--primary-color);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 3rem 0;
                border-radius: 0 0 20px 20px;
            }
            .table-of-contents {
                position: static;
            }
        }