:root {
            --primary-color: #ff6b35;
            --secondary-color: #f7931e;
            --accent-color: #ffd166;
            --dark-color: #2d3047;
            --light-color: #f8f9fa;
        }
        body {
            font-family: 'Segoe UI', system-ui, sans-serif;
            line-height: 1.7;
            color: #333;
            background: linear-gradient(135deg, #f8f9fa 0%, #e9ecef 100%);
        }
        .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: linear-gradient(rgba(45, 48, 71, 0.8), rgba(45, 48, 71, 0.9)), url('https://via.placeholder.com/1200x600') center/cover no-repeat;
            color: white;
            padding: 5rem 0;
            border-radius: 0 0 30px 30px;
            margin-bottom: 3rem;
        }
        .section-title {
            color: var(--dark-color);
            border-left: 5px solid var(--primary-color);
            padding-left: 1rem;
            margin: 2.5rem 0 1.5rem;
        }
        .content-card {
            background: white;
            border-radius: 15px;
            box-shadow: 0 10px 30px rgba(0,0,0,0.08);
            padding: 2rem;
            margin-bottom: 2rem;
            transition: transform 0.3s ease, box-shadow 0.3s ease;
            border: none;
        }
        .content-card:hover {
            transform: translateY(-5px);
            box-shadow: 0 15px 40px rgba(0,0,0,0.12);
        }
        .feature-icon {
            font-size: 2.5rem;
            color: var(--primary-color);
            margin-bottom: 1rem;
        }
        .highlight-text {
            background: linear-gradient(120deg, var(--accent-color) 0%, var(--accent-color) 100%);
            background-repeat: no-repeat;
            background-size: 100% 0.4em;
            background-position: 0 88%;
            font-weight: 700;
        }
        .img-container {
            border-radius: 12px;
            overflow: hidden;
            box-shadow: 0 8px 25px rgba(0,0,0,0.1);
            margin: 2rem 0;
        }
        .img-fluid {
            transition: transform 0.5s ease;
        }
        .img-fluid:hover {
            transform: scale(1.03);
        }
        .table-of-contents {
            background: linear-gradient(135deg, #fff5e6 0%, #ffe8cc 100%);
            border-radius: 15px;
            padding: 2rem;
            margin: 2rem 0;
            border-left: 5px solid var(--secondary-color);
        }
        .toc-item {
            padding: 0.5rem 0;
            border-bottom: 1px dashed #dee2e6;
        }
        .toc-item:last-child {
            border-bottom: none;
        }
        .key-feature {
            display: flex;
            align-items: flex-start;
            margin-bottom: 1.5rem;
        }
        .key-feature i {
            color: var(--primary-color);
            margin-right: 1rem;
            font-size: 1.5rem;
            margin-top: 0.3rem;
        }
        footer {
            background: var(--dark-color);
            color: white;
            padding: 3rem 0 2rem;
            margin-top: 4rem;
        }
        .social-links a {
            color: white;
            font-size: 1.5rem;
            margin-right: 1rem;
            transition: color 0.3s ease;
        }
        .social-links a:hover {
            color: var(--accent-color);
        }
        @media (max-width: 768px) {
            .hero-section {
                padding: 3rem 0;
                border-radius: 0 0 20px 20px;
            }
            .content-card {
                padding: 1.5rem;
            }
        }