:root {
      --primary: rgb(15, 118, 110);
      --primary-hover: rgb(13, 98, 92);
      --primary-light: rgba(15, 118, 110, 0.1);
      --dark-gray: #1e293b;
      --light-gray: #f1f5f9;
      --border-color: #e2e8f0;
      --text-main: #0f172a;
      --text-muted: #64748b;
      --transition: all 0.3s cubic-bezier(0.4, 0, 0.2, 1);
      --shadow: 0 4px 20px -2px rgba(15, 118, 110, 0.12);
      --radius: 12px;
      --container-width: 1200px;
    }

    * { box-sizing: border-box; margin: 0; padding: 0; }
    body { font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, sans-serif; color: var(--text-main); background: #f8fafc; }
    a { color: inherit; text-decoration: none; transition: var(--transition); }
    .container { width: 100%; max-width: var(--container-width); margin: 0 auto; padding: 0 24px; }

    
    .site-header { position: sticky; top: 0; z-index: 100; background: rgba(255, 255, 255, 0.85); backdrop-filter: blur(12px); border-bottom: 1px solid var(--border-color); }
    .header-container { display: flex; align-items: center; justify-content: space-between; height: 72px; }
    .logo { display: inline-flex; align-items: center; gap: 12px; }
    .logo img { height: 40px; }
    .logo span { font-size: 18px; font-weight: 800; color: var(--dark-gray); }
    .desktop-nav { display: flex; align-items: center; gap: 32px; }
    .desktop-nav a { font-size: 15px; font-weight: 500; }
    .desktop-nav a:hover { color: var(--primary); }
    .header-actions { display: flex; align-items: center; gap: 16px; }
    .nav-cta-btn { background: var(--primary); color: #fff; padding: 10px 24px; border-radius: 30px; font-size: 14px; font-weight: 600; }
    .drawer-trigger { display: none; flex-direction: column; justify-content: space-between; width: 24px; height: 18px; background: none; border: none; cursor: pointer; }
    .drawer-trigger span { width: 100%; height: 2px; background: var(--text-main); }

    
    .mobile-drawer-overlay { position: fixed; top: 0; left: 0; width: 100%; height: 100%; background: rgba(0,0,0,0.5); backdrop-filter: blur(4px); z-index: 150; opacity: 0; pointer-events: none; transition: var(--transition); }
    .mobile-drawer-overlay.active { opacity: 1; pointer-events: auto; }
    .mobile-drawer { position: fixed; top: 0; left: -320px; width: 300px; height: 100%; background: #fff; z-index: 160; display: flex; flex-direction: column; transition: var(--transition); }
    .mobile-drawer.active { left: 0; }
    .drawer-header { display: flex; align-items: center; justify-content: space-between; padding: 20px 24px; border-bottom: 1px solid var(--border-color); }
    .drawer-close { font-size: 28px; background: none; border: none; cursor: pointer; color: var(--text-muted); }
    .mobile-nav { padding: 24px; display: flex; flex-direction: column; gap: 20px; flex-grow: 1; overflow-y: auto; }
    .drawer-cta-btn { background: var(--primary); color: #fff; text-align: center; padding: 12px; border-radius: var(--radius); margin-top: auto; font-weight: 600; }
    .drawer-footer { padding: 24px; border-top: 1px solid var(--border-color); font-size: 13px; color: var(--text-muted); }

    
    .download-grid { display: grid; grid-template-columns: 1.2fr 1fr; gap: 60px; padding: 80px 0; }
    .download-title-area h1 { font-size: 40px; font-weight: 800; color: var(--dark-gray); margin-bottom: 20px; }
    .download-title-area p { font-size: 16px; color: var(--text-muted); margin-bottom: 40px; }
    
    .download-channels { display: flex; flex-direction: column; gap: 20px; }
    .channel-box { display: flex; align-items: center; justify-content: space-between; padding: 24px; background: #fff; border: 1px solid var(--border-color); border-radius: var(--radius); }
    .channel-left { display: flex; align-items: center; gap: 16px; }
    .channel-icon { font-size: 32px; width: 60px; height: 60px; background: var(--primary-light); color: var(--primary); display: flex; align-items: center; justify-content: center; border-radius: 50%; }
    .channel-info h3 { font-size: 18px; font-weight: 700; margin-bottom: 4px; }
    .channel-info p { font-size: 13px; color: var(--text-muted); }
    
    .download-action-btn { background: var(--primary); color: #fff; padding: 12px 28px; border-radius: 30px; font-weight: 600; font-size: 14px; }
    .download-action-btn:hover { background: var(--primary-hover); }

    .qrcode-panel { background: #fff; border: 1px solid var(--border-color); border-radius: var(--radius); padding: 40px; text-align: center; display: flex; flex-direction: column; align-items: center; justify-content: center; box-shadow: var(--shadow); }
    .qrcode-box { width: 220px; height: 220px; background: #000; display: flex; align-items: center; justify-content: center; color: #fff; font-size: 14px; margin-bottom: 20px; border-radius: 10px; }
    
    .installation-guide { padding: 80px 0; background: #fff; }
    .installation-guide h2 { font-size: 28px; font-weight: 800; text-align: center; margin-bottom: 50px; }
    .steps-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: 30px; }
    .step-card { text-align: center; padding: 30px; background: var(--silver-white); border-radius: var(--radius); }
    .step-num { width: 40px; height: 40px; background: var(--primary); color: #fff; border-radius: 50%; display: flex; align-items: center; justify-content: center; font-weight: bold; margin: 0 auto 20px auto; }
    .step-card h3 { font-size: 18px; font-weight: 700; margin-bottom: 12px; }
    .step-card p { font-size: 14px; color: var(--text-muted); }

    
    .site-footer { background: #0f172a; color: #94a3b8; padding: 80px 0 30px 0; border-top: 1px solid #1e293b; }
    .footer-container { display: grid; grid-template-columns: 1.5fr repeat(3, 1fr); gap: 40px; margin-bottom: 60px; }
    .footer-brand p { margin-top: 16px; font-size: 14px; }
    .footer-social { margin-top: 20px; font-size: 13px; }
    .footer-social .social-item { display: block; margin-bottom: 8px; }
    .footer-col h4 { color: #fff; font-size: 16px; margin-bottom: 20px; }
    .footer-col ul { list-style: none; }
    .footer-col ul li { margin-bottom: 12px; }
    .footer-col ul li a { font-size: 14px; }
    .footer-col ul li a:hover { color: #fff; }
    .footer-bottom { border-top: 1px solid #1e293b; padding-top: 30px; text-align: center; font-size: 13px; }
    .footer-bottom a { color: var(--primary); }

    @media (max-width: 900px) {
      .download-grid { grid-template-columns: 1fr; }
      .steps-grid { grid-template-columns: 1fr; }
    }
    @media (max-width: 768px) {
      .desktop-nav, .nav-cta-btn { display: none; }
      .drawer-trigger { display: flex; }
    }