:root {
            --primary-color: #1D7BFF;
            --dark-bg: #0f172a;
            --paper-bg: #f7f6f0;
            --card-bg: #ffffff;
            --text-main: #222222;
            --text-muted: #666666;
            --border-color: #e2e8f0;
            --font-serif: "Source Han Serif SC", "Noto Serif SC", "Georgia", serif;
            --font-sans: -apple-system, BlinkMacSystemFont, "Helvetica Neue", Arial, sans-serif;
        }

        * { margin: 0; padding: 0; box-sizing: border-box; }
        body { font-family: var(--font-sans); background-color: var(--paper-bg); color: var(--text-main); line-height: 1.6; }
        a { color: inherit; text-decoration: none; transition: color 0.3s; }
        a:hover { color: var(--primary-color); }

        header { background-color: var(--dark-bg); color: #ffffff; position: sticky; top: 0; z-index: 100; }
        .header-container { max-width: 1200px; margin: 0 auto; display: flex; align-items: center; justify-content: space-between; padding: 0 20px; height: 70px; }
        .logo { display: flex; align-items: center; gap: 10px; font-family: var(--font-serif); font-size: 24px; font-weight: 700; color: #ffffff; }
        .logo img { height: 40px; }
        .desktop-nav { display: flex; gap: 20px; }
        .desktop-nav a { color: #cbd5e1; font-weight: 500; padding: 8px 12px; }
        .menu-toggle { display: none; background: none; border: none; color: #ffffff; font-size: 24px; cursor: pointer; }

        
        .drawer-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.5); z-index: 998; opacity: 0; visibility: hidden; transition: all 0.3s; }
        .drawer-overlay.active { opacity: 1; visibility: visible; }
        .drawer { position: fixed; top: 0; left: -280px; width: 280px; height: 100%; background: var(--dark-bg); z-index: 999; padding: 20px; transition: all 0.3s; display: flex; flex-direction: column; gap: 20px; }
        .drawer.active { left: 0; }

        .download-container { max-width: 1000px; margin: 40px auto; padding: 0 20px; display: grid; grid-template-columns: 1fr 1fr; gap: 30px; }
        .download-card { background: #ffffff; border: 1px solid var(--border-color); border-radius: 8px; padding: 40px; text-align: center; box-shadow: 0 4px 6px rgba(0,0,0,0.02); }
        .download-card h2 { font-family: var(--font-serif); font-size: 26px; margin-bottom: 15px; }
        .download-card p { color: var(--text-muted); margin-bottom: 25px; font-size: 15px; }
        .qr-placeholder { width: 180px; height: 180px; background: #f1f5f9; margin: 0 auto 25px; display: flex; align-items: center; justify-content: center; border: 1px solid var(--border-color); font-size: 14px; color: #888; }
        .btn-download { display: inline-block; background: var(--primary-color); color: #ffffff; padding: 12px 30px; border-radius: 30px; font-weight: bold; transition: background 0.3s; }
        .btn-download:hover { background: #1565c0; color: #fff; }

        footer { background-color: var(--dark-bg); color: #94a3b8; padding: 40px 20px 20px; margin-top: 60px; }
        .footer-container { max-width: 1200px; margin: 0 auto; display: grid; grid-template-columns: repeat(auto-fit, minmax(250px, 1fr)); gap: 30px; padding-bottom: 30px; border-bottom: 1px solid rgba(255,255,255,0.1); }
        .footer-about h3, .footer-nav h3, .footer-links h3 { color: #ffffff; font-family: var(--font-serif); margin-bottom: 15px; font-size: 18px; }
        .footer-nav ul { list-style: none; }
        .footer-nav ul li { margin-bottom: 10px; }
        .friend-links .friend-content { display: flex; flex-wrap: wrap; gap: 10px; }
        .friend-links .friend-content a { color: #94a3b8; font-size: 14px; }
        .footer-bottom { max-width: 1200px; margin: 20px auto 0; text-align: center; font-size: 12px; }

        @media (max-width: 768px) {
            .desktop-nav { display: none; }
            .menu-toggle { display: block; }
            .download-container { grid-template-columns: 1fr; }
        }