:root {
            --ysa473-primary: #FF7139;
            --ysa473-primary-dark: #E66027;
            --ysa473-secondary: #002240;
            --ysa473-accent: #0060DF;
            --ysa473-text-main: #202124;
            --ysa473-text-light: #5f6368;
            --ysa473-bg-light: #F9FAFB;
            --ysa473-white: #ffffff;
            --ysa473-shadow: 0 12px 32px rgba(0, 0, 0, 0.08);
            --ysa473-radius: 16px;
            --ysa473-container-max: 1300px;
        }

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

        body {
            font-family: "Inter", "Segoe UI", "Microsoft YaHei", sans-serif;
            color: var(--ysa473-text-main);
            background-color: var(--ysa473-white);
            line-height: 1.6;
            overflow-x: hidden;
            word-break: keep-all;
        }

        /* Typography */
        h1, h2, h3 {
            line-height: 1.2;
            word-break: keep-all;
            white-space: normal;
        }

        .ysa473-fluid-h1 { font-size: clamp(2.5rem, 5vw + 1rem, 4.5rem); font-weight: 800; }
        .ysa473-fluid-h2 { font-size: clamp(1.8rem, 3vw + 0.5rem, 2.8rem); font-weight: 700; }
        .ysa473-fluid-p { font-size: clamp(1rem, 0.5vw + 0.8rem, 1.25rem); line-height: 1.8; }

        /* Navigation */
        .ysa473-nav-wrapper {
            position: fixed;
            top: 0;
            width: 100%;
            z-index: 1000;
            background: rgba(255, 255, 255, 0.9);
            backdrop-filter: blur(10px);
            border-bottom: 1px solid rgba(0,0,0,0.05);
            transition: all 0.3s ease;
        }

        .ysa473-nav-container {
            max-width: var(--ysa473-container-max);
            margin: 0 auto;
            padding: 0 24px;
            display: flex;
            align-items: center;
            justify-content: space-between;
            height: 80px;
            flex-wrap: wrap;
        }

        .ysa473-logo {
            display: flex;
            align-items: center;
            min-width: 0;
        }

        .ysa473-logo img {
            height: 40px;
            width: auto;
        }

        .ysa473-nav-menu {
            display: flex;
            list-style: none;
            gap: 16px;
            flex-wrap: wrap;
            min-width: 0;
        }

        .ysa473-nav-menu li a {
            text-decoration: none;
            color: var(--ysa473-text-light);
            font-weight: 500;
            font-size: 0.95rem;
            padding: 8px 12px;
            border-radius: 8px;
            transition: all 0.2s ease;
            white-space: nowrap;
        }

        .ysa473-nav-menu li a:hover {
            color: var(--ysa473-primary);
            background: rgba(255, 113, 57, 0.05);
        }

        .ysa473-nav-menu li a.ysa473-active {
            color: var(--ysa473-white);
            background: var(--ysa473-primary);
        }

        /* Hero Section */
        .ysa473-hero {
            padding: 160px 24px 80px;
            background: linear-gradient(135deg, #FFF5F2 0%, #FFFFFF 100%);
            position: relative;
            overflow: hidden;
            display: flex;
            flex-wrap: wrap;
            justify-content: center;
            text-align: center;
        }

        .ysa473-hero-content {
            max-width: 900px;
            min-width: 0;
            position: relative;
            z-index: 2;
        }

        .ysa473-hero-badge {
            display: inline-block;
            background: rgba(255, 113, 57, 0.1);
            color: var(--ysa473-primary);
            padding: 6px 16px;
            border-radius: 50px;
            font-weight: 600;
            margin-bottom: 24px;
        }

        .ysa473-hero h1 {
            color: var(--ysa473-secondary);
            margin-bottom: 24px;
        }

        .ysa473-hero p {
            color: var(--ysa473-text-light);
            margin-bottom: 40px;
            max-width: 700px;
            margin-left: auto;
            margin-right: auto;
        }

        /* Download Options Grid */
        .ysa473-download-section {
            padding: 80px 24px;
            background: var(--ysa473-bg-light);
            position: relative;
        }

        .ysa473-section-container {
            max-width: var(--ysa473-container-max);
            margin: 0 auto;
        }

        .ysa473-grid-background {
            background-image: url('images/download_os_grid.jpg');
            background-size: cover;
            background-position: center;
            border-radius: 32px;
            padding: 64px;
            display: flex;
            flex-wrap: wrap;
            gap: 32px;
            min-width: 0;
            box-shadow: var(--ysa473-shadow);
        }

        .ysa473-os-card {
            flex: 1;
            min-width: 280px;
            background: rgba(255, 255, 255, 0.95);
            backdrop-filter: blur(10px);
            padding: 40px;
            border-radius: var(--ysa473-radius);
            text-align: center;
            transition: transform 0.3s ease;
            display: flex;
            flex-direction: column;
            align-items: center;
        }

        .ysa473-os-card:hover {
            transform: translateY(-8px);
        }

        .ysa473-os-icon {
            font-size: 3rem;
            margin-bottom: 20px;
        }

        .ysa473-os-title {
            font-size: 1.5rem;
            font-weight: 700;
            margin-bottom: 12px;
        }

        .ysa473-btn-primary {
            background: var(--ysa473-primary);
            color: var(--ysa473-white);
            text-decoration: none;
            padding: 14px 32px;
            border-radius: 12px;
            font-weight: 600;
            transition: all 0.3s ease;
            display: inline-block;
            border: none;
            cursor: pointer;
            box-shadow: 0 4px 14px rgba(255, 113, 57, 0.3);
        }

        .ysa473-btn-primary:hover {
            background: var(--ysa473-primary-dark);
            box-shadow: 0 6px 20px rgba(255, 113, 57, 0.4);
        }

        /* Mobile App Section */
        .ysa473-mobile-section {
            padding: 96px 24px;
            display: flex;
            flex-wrap: wrap;
            align-items: center;
            max-width: var(--ysa473-container-max);
            margin: 0 auto;
            gap: 64px;
        }

        .ysa473-mobile-image {
            flex: 1;
            min-width: 320px;
        }

        .ysa473-mobile-image img {
            width: 100%;
            height: auto;
            border-radius: 24px;
            box-shadow: var(--ysa473-shadow);
        }

        .ysa473-mobile-text {
            flex: 1;
            min-width: 320px;
            word-break: break-word;
        }

        .ysa473-mobile-text h2 {
            margin-bottom: 24px;
            color: var(--ysa473-secondary);
        }

        .ysa473-qr-area {
            display: flex;
            align-items: center;
            gap: 24px;
            margin-top: 32px;
            background: white;
            padding: 24px;
            border-radius: 16px;
            border: 1px solid #eee;
        }

        .ysa473-qr-placeholder {
            width: 120px;
            height: 120px;
            background: #f0f0f0;
            display: flex;
            align-items: center;
            justify-content: center;
            border-radius: 8px;
            font-size: 0.8rem;
            color: #999;
            text-align: center;
            padding: 10px;
        }

        /* Features Section */
        .ysa473-features {
            padding: 80px 24px;
            background: var(--ysa473-secondary);
            color: var(--ysa473-white);
        }

        .ysa473-features-grid {
            display: grid;
            grid-template-columns: repeat(auto-fit, minmax(300px, 1fr));
            gap: 40px;
            max-width: var(--ysa473-container-max);
            margin: 0 auto;
        }

        .ysa473-feature-item {
            padding: 32px;
            border-left: 2px solid var(--ysa473-primary);
        }

        .ysa473-feature-item h3 {
            margin-bottom: 16px;
            font-size: 1.4rem;
        }

        .ysa473-feature-item p {
            color: rgba(255, 255, 255, 0.7);
        }

        /* Dynamic Content Area */
        .ysa473-news-section {
            padding: 80px 24px;
            max-width: var(--ysa473-container-max);
            margin: 0 auto;
        }

        .ysa473-news-header {
            display: flex;
            justify-content: space-between;
            align-items: flex-end;
            margin-bottom: 48px;
            flex-wrap: wrap;
            gap: 16px;
        }

        /* Footer */
        .ysa473-footer {
            background: var(--ysa473-bg-light);
            padding: 80px 24px 40px;
            border-top: 1px solid #eee;
        }

        .ysa473-footer-content {
            max-width: var(--ysa473-container-max);
            margin: 0 auto;
            display: flex;
            flex-wrap: wrap;
            gap: 48px;
        }

        .ysa473-footer-brand {
            flex: 2;
            min-width: 280px;
        }

        .ysa473-footer-brand-name {
            font-size: 1.5rem;
            font-weight: 800;
            color: var(--ysa473-secondary);
            margin-bottom: 16px;
        }

        .ysa473-footer-links {
            flex: 1;
            min-width: 150px;
        }

        .ysa473-footer-links h4 {
            margin-bottom: 24px;
            font-size: 1rem;
            color: var(--ysa473-text-main);
        }

        .ysa473-footer-links ul {
            list-style: none;
        }

        .ysa473-footer-links ul li {
            margin-bottom: 12px;
        }

        .ysa473-footer-links ul li a {
            text-decoration: none;
            color: var(--ysa473-text-light);
            transition: color 0.2s;
        }

        .ysa473-footer-links ul li a:hover {
            color: var(--ysa473-primary);
        }

        .ysa473-copyright {
            max-width: var(--ysa473-container-max);
            margin: 64px auto 0;
            padding-top: 32px;
            border-top: 1px solid #eee;
            color: var(--ysa473-text-light);
            font-size: 0.9rem;
            text-align: center;
        }

        /* Responsive */
        @media (max-width: 768px) {
            .ysa473-nav-container {
                height: auto;
                padding: 16px;
            }
            .ysa473-nav-menu {
                margin-top: 16px;
                justify-content: center;
                width: 100%;
            }
            .ysa473-grid-background {
                padding: 24px;
            }
            .ysa473-os-card {
                padding: 24px;
            }
            .ysa473-mobile-section {
                gap: 32px;
                padding: 64px 24px;
            }
        }

        /* Utility */
        .ysa473-text-gradient {
            background: linear-gradient(90deg, #FF7139, #FF4E00);
            -webkit-background-clip: text;
            -webkit-text-fill-color: transparent;
        }