:root {
            --primary-color: #FF9933;
            --secondary-color: #138808;
            --accent-color: #000080;
            --text-color: #333333;
            --light-bg: #f8f9fa;
        }
        body {
            font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
            line-height: 1.7;
            color: var(--text-color);
            background-color: #ffffff;
        }
        .logo {
            font-family: 'Georgia', serif;
            font-weight: bold;
            color: var(--accent-color);
            text-shadow: 2px 2px 4px rgba(0,0,0,0.1);
        }
        .nav-custom {
            background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
            box-shadow: 0 4px 12px rgba(0,0,0,0.1);
        }
        .nav-link {
            color: white !important;
            font-weight: 500;
            transition: all 0.3s ease;
            padding: 10px 15px !important;
        }
        .nav-link:hover {
            background-color: rgba(255,255,255,0.2);
            border-radius: 5px;
            transform: translateY(-2px);
        }
        h1, h2, h3 {
            color: var(--accent-color);
            margin-bottom: 1rem;
        }
        h1 {
            border-bottom: 3px solid var(--primary-color);
            padding-bottom: 10px;
        }
        h2 {
            border-left: 5px solid var(--secondary-color);
            padding-left: 15px;
            margin-top: 2.5rem;
        }
        h3 {
            color: var(--primary-color);
            margin-top: 1.8rem;
        }
        .content-section {
            margin-bottom: 3rem;
            padding: 2rem;
            background-color: white;
            border-radius: 10px;
            box-shadow: 0 5px 15px rgba(0,0,0,0.05);
        }
        .highlight-box {
            background: linear-gradient(135deg, var(--light-bg), #e9ecef);
            border-left: 4px solid var(--primary-color);
            padding: 1.5rem;
            margin: 1.5rem 0;
            border-radius: 0 8px 8px 0;
        }
        .key-term {
            font-weight: bold;
            color: var(--secondary-color);
        }
        .image-container {
            text-align: center;
            margin: 2rem 0;
        }
        .image-caption {
            font-style: italic;
            color: #666;
            margin-top: 0.5rem;
            font-size: 0.9rem;
        }
        .fact-box {
            background-color: var(--light-bg);
            border-radius: 8px;
            padding: 1.5rem;
            margin: 1.5rem 0;
            border: 1px solid #dee2e6;
        }
        .fact-title {
            color: var(--accent-color);
            font-weight: bold;
            margin-bottom: 0.5rem;
        }
        footer {
            background-color: var(--accent-color);
            color: white;
            padding: 2rem 0;
            margin-top: 3rem;
        }
        .back-to-top {
            position: fixed;
            bottom: 20px;
            right: 20px;
            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 4px 8px rgba(0,0,0,0.2);
            transition: all 0.3s ease;
            z-index: 1000;
        }
        .back-to-top:hover {
            background-color: var(--secondary-color);
            transform: translateY(-5px);
            color: white;
        }
        @media (max-width: 768px) {
            .content-section {
                padding: 1.5rem;
            }
            h1 {
                font-size: 1.8rem;
            }
            h2 {
                font-size: 1.5rem;
            }
        }