:root {
            --primary-color: #ff6b35;
            --secondary-color: #1a535c;
            --accent-color: #4ecdc4;
            --text-color: #333333;
            --light-bg: #f7fff7;
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.7;
            color: var(--text-color);
            background-color: var(--light-bg);
        }
        .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(rgba(26, 83, 92, 0.8), rgba(26, 83, 92, 0.9)), url('https://via.placeholder.com/1600x900') center/cover no-repeat;
            color: white;
            padding: 100px 0;
            text-align: center;
        }
        h1, h2, h3 {
            color: var(--secondary-color);
            margin-bottom: 1.2rem;
        }
        h1 {
            font-size: 2.8rem;
            font-weight: 800;
            text-shadow: 1px 1px 3px rgba(0,0,0,0.2);
        }
        h2 {
            font-size: 2.2rem;
            border-left: 5px solid var(--primary-color);
            padding-left: 15px;
            margin-top: 2.5rem;
        }
        h3 {
            font-size: 1.8rem;
            color: var(--primary-color);
            margin-top: 2rem;
        }
        .content-section {
            padding: 60px 0;
        }
        .highlight-box {
            background-color: white;
            border-radius: 10px;
            padding: 25px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.05);
            margin: 25px 0;
            border-left: 4px solid var(--accent-color);
        }
        .fact-box {
            background-color: var(--secondary-color);
            color: white;
            border-radius: 8px;
            padding: 20px;
            margin: 20px 0;
        }
        .img-container {
            border-radius: 10px;
            overflow: hidden;
            box-shadow: 0 8px 20px rgba(0,0,0,0.1);
            margin: 30px 0;
        }
        .img-container img {
            width: 100%;
            height: auto;
            transition: transform 0.5s ease;
        }
        .img-container:hover img {
            transform: scale(1.03);
        }
        .key-point {
            background-color: rgba(255, 107, 53, 0.1);
            border-radius: 8px;
            padding: 15px;
            margin: 15px 0;
            border-left: 3px solid var(--primary-color);
        }
        .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: 40px 0 20px;
        }
        .back-to-top {
            position: fixed;
            bottom: 30px;
            right: 30px;
            background-color: 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 3px 10px rgba(0,0,0,0.2);
            z-index: 1000;
            opacity: 0;
            transition: opacity 0.3s;
        }
        .back-to-top.show {
            opacity: 1;
        }
        @media (max-width: 768px) {
            h1 {
                font-size: 2.2rem;
            }
            h2 {
                font-size: 1.8rem;
            }
            .hero-section {
                padding: 70px 0;
            }
        }