:root {
            --primary-color: #2c3e50;
            --secondary-color: #3498db;
            --accent-color: #e74c3c;
            --text-color: #333;
            --bg-color: #f8f9fa;
            --white: #fff;
            --font-family: system-ui, -apple-system, sans-serif;
            --transition: all 0.3s ease;
            --focus-outline: 2px solid var(--secondary-color);
        }

        * {
            box-sizing: border-box;
            margin: 0;
            padding: 0;
        }

        body {
            font-family: var(--font-family);
            line-height: 1.6;
            color: var(--text-color);
            background-color: var(--bg-color);
        }

        /* Skip Link for Accessibility */
        .skip-link {
            position: absolute;
            top: -40px;
            left: 6px;
            background: var(--accent-color);
            color: var(--white);
            padding: 8px;
            text-decoration: none;
            border-radius: 0 0 4px 4px;
            z-index: 200;
            transition: top 0.3s;
        }

        .skip-link:focus {
            top: 6px;
        }

        /* Header */
        header {
            background: var(--primary-color);
            color: var(--white);
            padding: 1rem;
            position: sticky;
            top: 0;
            z-index: 100;
            box-shadow: 0 2px 10px rgba(0,0,0,0.1);
        }

        .header-container {
            display: flex;
            justify-content: space-between;
            align-items: center;
            max-width: 1200px;
            margin: 0 auto;
        }

        .logo {
            font-size: 1.5rem;
            font-weight: bold;
            text-decoration: none;
            color: var(--white);
        }

        /* Navigation - Semantic and Accessible */
        nav[role="navigation"] {
            /* CSS for nav */
        }

        nav ul {
            display: flex;
            list-style: none;
            gap: 2rem;
        }

        nav a {
            color: var(--white);
            text-decoration: none;
            transition: var(--transition);
            display: block;
            padding: 0.5rem 0;
        }

        nav a:hover,
        nav a:focus {
            color: var(--secondary-color);
            outline: var(--focus-outline);
            outline-offset: 2px;
        }

        /* Focus Visible Polyfill Support */
        @supports (outline: none) {
            nav a:focus-visible {
                outline: var(--focus-outline);
            }
        }

        /* Dropdown Menu Improvements with Accessibility */
        .dropdown {
            position: relative;
        }

        .dropdown > a {
            cursor: pointer;
        }

        .submenu {
            display: none;
            position: absolute;
            top: 100%;
            left: 0;
            background: var(--primary-color);
            min-width: 200px;
            box-shadow: 0 4px 10px rgba(0,0,0,0.2);
            border-radius: 0 0 8px 8px;
            z-index: 101;
            flex-direction: column;
            gap: 0;
            list-style: none;
        }

        .submenu li {
            border-bottom: 1px solid rgba(255,255,255,0.1);
        }

        .submenu li:last-child {
            border-bottom: none;
        }

        .submenu a {
            padding: 1rem 1.5rem;
            white-space: nowrap;
        }

        .submenu a:hover,
        .submenu a:focus {
            background: var(--secondary-color);
            color: var(--white);
            outline: var(--focus-outline);
            outline-offset: 2px;
        }

        /* Show submenu on hover/focus for desktop */
        @media (min-width: 769px) {
            .dropdown:hover .submenu,
            .dropdown:focus-within .submenu {
                display: flex;
            }

            .menu-toggle {
                display: none;
            }
        }

        /* Mobile Menu Toggle */
        .menu-toggle {
            display: block;
            background: none;
            border: none;
            color: var(--white);
            font-size: 1.5rem;
            cursor: pointer;
        }

        .menu-toggle:focus {
            outline: var(--focus-outline);
            outline-offset: 2px;
        }

        /* Mobile Navigation */
        @media (max-width: 768px) {
            .header-container {
                flex-direction: column;
                gap: 1rem;
            }

            nav ul {
                display: none;
                flex-direction: column;
                width: 100%;
                gap: 0;
                background: var(--primary-color);
            }

            nav ul.active {
                display: flex;
            }

            .submenu {
                position: static;
                display: none;
                background: rgba(0,0,0,0.2);
                box-shadow: none;
                border-radius: 0;
                margin-left: 1rem;
            }

            .dropdown.active .submenu {
                display: flex;
            }

            .submenu a {
                padding: 0.75rem 1rem;
            }
        }

        /* Main */
        main {
            max-width: 1200px;
            margin: 0 auto;
            padding: 2rem 1rem;
        }

        /* Hero Section - Optimized with keywords */
        .hero {
            text-align: center;
            padding: 3rem 1rem;
            background: linear-gradient(to right, var(--secondary-color), var(--primary-color));
            color: var(--white);
            margin-bottom: 2rem;
            border-radius: 8px;
        }

        .hero h1 {
            font-size: 2.5rem;
            margin-bottom: 1rem;
        }

        .hero p {
            font-size: 1.2rem;
            max-width: 600px;
            margin: 0 auto;
        }

        /* Sections - Semantic with keywords in headings */
        section {
            margin-bottom: 3rem;
        }

        h2 {
            color: var(--primary-color);
            margin-bottom: 1rem;
            font-size: 2rem;
        }

        h3 {
            color: var(--secondary-color);
            margin-bottom: 0.5rem;
        }

        /* Grid for Content - Using Flex for simplicity */
        .content-grid {
            display: flex;
            flex-wrap: wrap;
            gap: 2rem;
        }

        .card {
            flex: 1 1 300px;
            background: var(--white);
            padding: 1.5rem;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            transition: var(--transition);
        }

        .card:hover,
        .card:focus-within {
            transform: translateY(-5px);
            box-shadow: 0 5px 15px rgba(0,0,0,0.2);
        }

        .btn {
            display: inline-block;
            background: var(--secondary-color);
            color: var(--white);
            padding: 0.75rem 1.5rem;
            text-decoration: none;
            border-radius: 4px;
            margin-top: 1rem;
            transition: var(--transition);
        }

        .btn:hover {
            background: var(--primary-color);
        }

        /* Guide Styles */
        .guide article {
            background: var(--white);
            padding: 2rem;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            margin-bottom: 2rem;
        }

        .guide h3 {
            margin-top: 1.5rem;
        }

        .guide ul, .guide ol {
            margin-left: 2rem;
            margin-bottom: 1rem;
        }

        .guide table {
            width: 100%;
            border-collapse: collapse;
            margin: 1rem 0;
        }

        .guide th, .guide td {
            border: 1px solid #ddd;
            padding: 0.75rem;
            text-align: left;
        }

        .guide th {
            background: var(--bg-color);
        }

        .references {
            background: var(--bg-color);
            padding: 1.5rem;
            border-radius: 8px;
        }

        .references ol {
            margin-left: 1rem;
        }

        .references li {
            margin-bottom: 0.5rem;
        }

        .guide a {
            color: var(--secondary-color);
            text-decoration: none;
        }

        .guide a:hover {
            text-decoration: underline;
        }

        /* FAQ Styles */
        .faq-item {
            background: var(--white);
            margin-bottom: 1rem;
            border-radius: 8px;
            box-shadow: 0 2px 5px rgba(0,0,0,0.1);
            overflow: hidden;
        }

        .faq-question {
            background: var(--secondary-color);
            color: var(--white);
            padding: 1rem;
            cursor: pointer;
            font-weight: bold;
            transition: var(--transition);
        }

        .faq-question:hover {
            background: var(--primary-color);
        }

        .faq-answer {
            padding: 1rem;
            display: none;
        }

        .faq-answer.active {
            display: block;
        }

        /* Footer - Enhanced with Flexbox, Mobile-First Responsive Design */
        footer {
            background: var(--primary-color);
            color: var(--white);
            padding: 2rem 1rem 1rem;
            margin-top: 3rem;
        }

        .footer-container {
            max-width: 1200px;
            margin: 0 auto;
        }

        .footer-top {
            text-align: center;
            margin-bottom: 1.5rem;
        }

        .footer-top h2 {
            color: var(--white);
            font-size: 1.5rem;
            margin-bottom: 0.5rem;
        }

        .footer-top p {
            font-size: 0.9rem;
        }

        .footer-top a {
            color: var(--secondary-color);
            text-decoration: none;
        }

        .footer-top a:hover {
            text-decoration: underline;
        }

        .footer-menu {
            display: flex;
            flex-direction: column;
            gap: 1rem;
            margin-bottom: 1.5rem;
        }

        .footer-menu ul {
            display: flex;
            flex-direction: column;
            list-style: none;
            gap: 0.5rem;
            text-align: center;
        }

        .footer-menu li {
            margin: 0;
        }

        .footer-menu a {
            color: var(--white);
            text-decoration: none;
            padding: 0.5rem;
            font-size: 0.9rem;
            transition: var(--transition);
        }

        .footer-menu a:hover,
        .footer-menu a:focus {
            color: var(--secondary-color);
            outline: var(--focus-outline);
            outline-offset: 2px;
        }

        .footer-social {
            display: flex;
            justify-content: center;
            gap: 1rem;
            margin-bottom: 1rem;
        }

        .social-icon {
            display: flex;
            align-items: center;
            justify-content: center;
            width: 40px;
            height: 40px;
            background: var(--secondary-color);
            color: var(--white);
            text-decoration: none;
            border-radius: 50%;
            font-size: 1.2rem;
            transition: var(--transition);
        }

        .social-icon:hover,
        .social-icon:focus {
            background: var(--accent-color);
            transform: scale(1.1);
            outline: var(--focus-outline);
            outline-offset: 2px;
        }

        .footer-bottom {
            text-align: center;
            padding-top: 1rem;
            border-top: 1px solid rgba(255, 255, 255, 0.1);
            font-size: 0.8rem;
        }

        /* Responsive Design: Desktop */
        @media (min-width: 769px) {
            .footer-menu {
                flex-direction: row;
                justify-content: center;
                align-items: center;
            }

            .footer-menu ul {
                display: flex;
                flex-direction: row;
                gap: 2rem;
                text-align: left;
            }

            .footer-menu li {
                margin: 0;
            }

            .footer-social {
                justify-content: center;
                gap: 1.5rem;
            }

            .social-icon {
                width: 45px;
                height: 45px;
                font-size: 1.4rem;
            }
        }

        /* Responsive Design */
        @media (max-width: 768px) {
            .hero h1 {
                font-size: 2rem;
            }

            .content-grid {
                flex-direction: column;
            }

            .guide article {
                padding: 1rem;
            }
        }