:root {
      --blue: #1769ff;
      --blue-dark: #0c46d9;
      --ink: #111827;
      --muted: #677083;
      --line: #e6ebf2;
      --soft: #f5f8fc;
      --mint: #19c59c;
      --amber: #f6b33f;
      --violet: #7c5cff;
      --radius: 8px;
      font-family: Inter, -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
        "Microsoft YaHei", Arial, sans-serif;
    }

    * {
      box-sizing: border-box;
    }

    body {
      margin: 0;
      color: var(--ink);
      background: #fff;
      line-height: 1.5;
    }

    a {
      color: inherit;
      text-decoration: none;
    }

    .shell {
      width: min(1160px, calc(100% - 40px));
      margin: 0 auto;
    }

    .nav {
      position: sticky;
      top: 0;
      z-index: 20;
      background: rgba(255, 255, 255, 0.92);
      border-bottom: 1px solid rgba(230, 235, 242, 0.9);
      backdrop-filter: blur(16px);
    }

    .nav-inner {
      height: 72px;
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 22px;
    }

    .brand {
      display: inline-flex;
      align-items: center;
      gap: 12px;
      font-weight: 800;
      font-size: 22px;
    }

    .brand-logo {
      width: 34px;
      height: 34px;
      border-radius: 8px;
      display: block;
      object-fit: cover;
      box-shadow: 0 12px 24px rgba(23, 105, 255, 0.28);
    }

    .nav-links {
      display: flex;
      align-items: center;
      gap: 28px;
      color: #344054;
      font-size: 15px;
    }

    .ghost-btn,
    .primary-btn,
    .download-card,
    .copy-btn {
      border-radius: var(--radius);
    }

    .ghost-btn,
    .primary-btn,
    .copy-btn {
      border: 0;
      display: inline-flex;
      align-items: center;
      justify-content: center;
      font: inherit;
      cursor: pointer;
      font-weight: 750;
      transition: transform 0.2s ease, box-shadow 0.2s ease;
    }

    .ghost-btn {
      height: 40px;
      padding: 0 16px;
      color: var(--blue);
      background: #eef5ff;
    }

    .primary-btn {
      min-height: 52px;
      padding: 0 22px;
      color: #fff;
      background: var(--blue);
      box-shadow: 0 16px 28px rgba(23, 105, 255, 0.28);
    }

    .ghost-btn:hover,
    .primary-btn:hover,
    .copy-btn:hover {
      transform: translateY(-1px);
    }

    .hero {
      overflow: hidden;
      background: linear-gradient(155deg, #eff6ff 0%, #ffffff 44%, #eefaff 100%);
    }

    .hero-inner {
      min-height: 640px;
      display: grid;
      grid-template-columns: 1fr 0.95fr;
      align-items: center;
      gap: 58px;
      padding: 76px 0 64px;
    }

    .eyebrow {
      display: inline-flex;
      align-items: center;
      gap: 8px;
      margin-bottom: 18px;
      padding: 8px 12px;
      border: 1px solid #d6e5ff;
      border-radius: 999px;
      color: var(--blue-dark);
      background: rgba(255, 255, 255, 0.85);
      font-size: 14px;
      font-weight: 800;
    }

    .dot {
      width: 8px;
      height: 8px;
      border-radius: 50%;
      background: var(--mint);
      box-shadow: 0 0 0 6px rgba(25, 197, 156, 0.14);
    }

    h1 {
      margin: 0;
      max-width: 650px;
      font-size: clamp(42px, 6vw, 70px);
      line-height: 1.04;
      letter-spacing: 0;
    }

    .lead {
      max-width: 590px;
      margin: 26px 0 34px;
      color: #4e5a70;
      font-size: 20px;
    }

    .hero-actions {
      display: flex;
      flex-wrap: wrap;
      gap: 14px;
      margin-bottom: 26px;
    }

    .system-note {
      display: flex;
      flex-wrap: wrap;
      gap: 16px;
      color: #607089;
      font-size: 14px;
    }

    .system-note span {
      display: inline-flex;
      align-items: center;
      gap: 7px;
    }

    .system-note span::before {
      content: "";
      width: 16px;
      height: 16px;
      border-radius: 50%;
      background: #e8f5ff;
      border: 5px solid var(--blue);
    }

    .visual {
      position: relative;
      min-height: 520px;
      display: grid;
      place-items: center;
    }

    .qr-panel {
      position: relative;
      width: min(390px, 88vw);
      padding: 28px;
      border: 1px solid rgba(220, 231, 247, 0.9);
      border-radius: 22px;
      background: rgba(255, 255, 255, 0.92);
      box-shadow: 0 34px 72px rgba(17, 42, 85, 0.16);
      backdrop-filter: blur(12px);
    }

    .qr-box {
      width: 210px;
      aspect-ratio: 1;
      margin: 0 auto 22px;
      padding: 16px;
      border: 1px solid var(--line);
      border-radius: 18px;
      background: #fff;
      display: grid;
      grid-template-columns: repeat(7, 1fr);
      gap: 6px;
    }

    .qr-box i {
      border-radius: 3px;
      background: #111827;
    }

    .qr-box i:nth-child(3n),
    .qr-box i:nth-child(5n) {
      background: #1769ff;
    }

    .qr-box i:nth-child(8n) {
      opacity: 0;
    }

    .qr-panel h2 {
      margin: 0 0 8px;
      text-align: center;
      font-size: 24px;
    }

    .qr-panel p {
      margin: 0;
      text-align: center;
      color: var(--muted);
    }

    .floating-badge {
      position: absolute;
      right: 12px;
      bottom: 50px;
      padding: 14px 16px;
      border: 1px solid var(--line);
      border-radius: 16px;
      background: #fff;
      box-shadow: 0 18px 40px rgba(18, 34, 64, 0.12);
      font-weight: 850;
    }

    section {
      padding: 86px 0;
    }

    .section-head {
      max-width: 720px;
      margin: 0 auto 38px;
      text-align: center;
    }

    h2 {
      margin: 0 0 14px;
      font-size: clamp(30px, 4vw, 44px);
      line-height: 1.12;
    }

    .section-head p {
      margin: 0;
      color: var(--muted);
      font-size: 18px;
    }

    .download-grid {
      display: grid;
      grid-template-columns: repeat(2, 1fr);
      gap: 22px;
    }

    .download-card {
      position: relative;
      overflow: hidden;
      min-height: 320px;
      padding: 30px;
      border: 1px solid var(--line);
      background: #fff;
      box-shadow: 0 18px 42px rgba(18, 34, 64, 0.06);
    }

    .download-card::after {
      content: "";
      position: absolute;
      width: 190px;
      height: 190px;
      right: -70px;
      top: -70px;
      border-radius: 50%;
      background: rgba(23, 105, 255, 0.08);
    }

    .platform {
      display: flex;
      align-items: center;
      gap: 14px;
      margin-bottom: 24px;
    }

    .platform-icon {
      width: 56px;
      height: 56px;
      border-radius: 16px;
      display: grid;
      place-items: center;
      color: #fff;
      background: var(--blue);
    }

    .platform-icon svg {
      width: 30px;
      height: 30px;
    }

    .platform h3 {
      margin: 0 0 4px;
      font-size: 24px;
    }

    .platform span {
      color: var(--muted);
      font-size: 14px;
    }

    .version-list {
      display: grid;
      gap: 12px;
      margin: 22px 0;
      color: #4f5c72;
      font-size: 15px;
    }

    .version-list div {
      display: flex;
      justify-content: space-between;
      gap: 18px;
      padding-bottom: 12px;
      border-bottom: 1px solid #edf1f7;
    }

    .version-list strong {
      color: var(--ink);
    }

    .copy-row {
      display: grid;
      grid-template-columns: 1fr auto;
      gap: 10px;
      margin-top: 12px;
    }

    .copy-row code {
      min-width: 0;
      padding: 12px;
      border: 1px solid var(--line);
      border-radius: var(--radius);
      background: #f8fafc;
      color: #475467;
      overflow: hidden;
      text-overflow: ellipsis;
      white-space: nowrap;
    }

    .copy-btn {
      min-height: 44px;
      padding: 0 14px;
      color: var(--blue);
      background: #eef5ff;
    }

    .steps {
      background: var(--soft);
    }

    .step-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }

    .step-card,
    .security-card {
      padding: 26px;
      border: 1px solid var(--line);
      border-radius: var(--radius);
      background: #fff;
      box-shadow: 0 14px 34px rgba(18, 34, 64, 0.05);
    }

    .step-number {
      width: 42px;
      height: 42px;
      margin-bottom: 22px;
      border-radius: 50%;
      display: grid;
      place-items: center;
      color: #fff;
      background: var(--blue);
      font-weight: 900;
    }

    .step-card h3,
    .security-card h3 {
      margin: 0 0 10px;
      font-size: 21px;
    }

    .step-card p,
    .security-card p {
      margin: 0;
      color: var(--muted);
    }

    .security-grid {
      display: grid;
      grid-template-columns: repeat(3, 1fr);
      gap: 20px;
    }

    .security-icon {
      width: 46px;
      height: 46px;
      margin-bottom: 20px;
      border-radius: 14px;
      display: grid;
      place-items: center;
      color: #fff;
      font-weight: 900;
    }

    .footer {
      padding: 42px 0;
      border-top: 1px solid var(--line);
      background: #fbfcfe;
    }

    .footer-row {
      display: flex;
      align-items: center;
      justify-content: space-between;
      gap: 18px;
      color: #7a8598;
      font-size: 14px;
    }

    @media (max-width: 920px) {
      .nav-links {
        display: none;
      }

      .hero-inner,
      .download-grid,
      .step-grid,
      .security-grid {
        grid-template-columns: 1fr;
      }

      .hero-inner {
        min-height: auto;
        gap: 34px;
        padding-top: 52px;
      }
    }

    @media (max-width: 620px) {
      .shell {
        width: min(100% - 28px, 1160px);
      }

      .nav-inner {
        height: 64px;
      }

      .brand {
        font-size: 19px;
      }

      section {
        padding: 62px 0;
      }

      .lead {
        font-size: 17px;
      }

      .hero-actions .primary-btn,
      .hero-actions .ghost-btn {
        width: 100%;
      }

      .visual {
        min-height: 390px;
      }

      .floating-badge {
        display: none;
      }

      .download-card,
      .qr-panel {
        padding: 22px;
      }

      .copy-row {
        grid-template-columns: 1fr;
      }

      .footer-row {
        align-items: flex-start;
        flex-direction: column;
      }
    }