:root {
    --bg: #0b1721;
    --bg-soft: #132532;
    --panel: #182b38;
    --text: #f3f8fb;
    --muted: #a8bac7;
  
    --ink: #102331;
    --ink-soft: #526879;
  
    --brand: #69b9ff;
    --brand-strong: #298fe5;
    --brand-soft: #eaf6ff;
  
    --white: #ffffff;
  
    --line: rgba(136, 174, 198, 0.28);
    --line-light: #d7e3ea;
  
    --radius-large: 28px;
    --radius-medium: 18px;
  
    --shadow: 0 22px 60px rgba(3, 17, 27, 0.16);
  
    --container: 1180px;
  }
  
  *,
  *::before,
  *::after {
    box-sizing: border-box;
  }
  
  html {
    scroll-behavior: smooth;
  }
  
  body {
    margin: 0;
    overflow-x: hidden;
  
    color: var(--text);
    background: var(--bg);
  
    font-family:
      Inter,
      "PingFang SC",
      "Microsoft YaHei",
      system-ui,
      -apple-system,
      sans-serif;
  
    line-height: 1.7;
    text-rendering: optimizeLegibility;
  }
  
  img {
    display: block;
    max-width: 100%;
    height: auto;
  }
  
  a {
    color: inherit;
    text-decoration: none;
  }
  
  button,
  a {
    -webkit-tap-highlight-color: transparent;
  }
  
  :focus-visible {
    outline: 3px solid rgba(105, 185, 255, 0.55);
    outline-offset: 4px;
  }
  
  .container {
    width: min(calc(100% - 40px), var(--container));
    margin-inline: auto;
  }
  
  .skip-link {
    position: fixed;
    top: 12px;
    left: 12px;
    z-index: 999;
  
    padding: 10px 14px;
  
    color: var(--ink);
    background: var(--white);
  
    border-radius: 10px;
  
    transform: translateY(-160%);
  }
  
  .skip-link:focus {
    transform: translateY(0);
  }
  
  /* Header */
  
  .site-header {
    position: sticky;
    top: 0;
    z-index: 50;
  
    border-bottom: 1px solid transparent;
  
    background: rgba(11, 23, 33, 0.88);
    backdrop-filter: blur(18px);
  
    transition:
      border-color 180ms ease,
      background 180ms ease;
  }
  
  .site-header.is-scrolled {
    border-color: var(--line);
    background: rgba(11, 23, 33, 0.96);
  }
  
  .nav-shell {
    min-height: 72px;
  
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
  
    gap: 30px;
  }
  
  .brand img {
    width: 132px;
    object-fit: contain;
  }
  
  .desktop-nav {
    justify-self: center;
  
    display: flex;
    gap: 28px;
  }
  
  .desktop-nav a {
    color: #c7d4dc;
    font-size: 14px;
  }
  
  .desktop-nav a:hover {
    color: var(--white);
  }
  
  /* Buttons */
  
  .button {
    display: inline-flex;
    min-height: 48px;
  
    align-items: center;
    justify-content: center;
  
    padding: 0 22px;
  
    color: #06141d;
    background: linear-gradient(
      135deg,
      #8fd0ff,
      var(--brand)
    );
  
    border: 1px solid rgba(255, 255, 255, 0.2);
    border-radius: 12px;
  
    font-weight: 800;
  
    box-shadow: 0 12px 30px rgba(41, 143, 229, 0.2);
  
    transition:
      transform 180ms ease,
      box-shadow 180ms ease;
  }
  
  .button:hover {
    transform: translateY(-2px);
  
    box-shadow: 0 16px 36px rgba(41, 143, 229, 0.28);
  }
  
  .button-small {
    min-height: 42px;
    padding-inline: 18px;
    font-size: 14px;
  }
  
  .text-link,
  .inline-arrow {
    color: var(--brand);
    font-weight: 750;
  }
  
  .text-link:hover,
  .inline-arrow:hover {
    text-decoration: underline;
    text-underline-offset: 5px;
  }
  
  /* Typography */
  
  h1,
  h2,
  h3,
  p {
    margin-top: 0;
  }
  
  h1 {
    max-width: 740px;
  
    margin-bottom: 22px;
  
    font-size: clamp(42px, 5.2vw, 70px);
    line-height: 1.08;
    letter-spacing: -0.045em;
  }
  
  h2 {
    margin-bottom: 14px;
  
    font-size: clamp(30px, 3.3vw, 46px);
    line-height: 1.18;
    letter-spacing: -0.035em;
  }
  
  h3 {
    line-height: 1.35;
  }
  
  .eyebrow {
    margin: 0 0 10px;
  
    color: var(--brand);
  
    font-size: 12px;
    font-weight: 900;
    letter-spacing: 0.12em;
    text-transform: uppercase;
  }
  
  /* Hero */
  
  .hero {
    position: relative;
    overflow: hidden;
  
    padding: 72px 0 58px;
  
    background:
      radial-gradient(
        circle at 80% 20%,
        rgba(30, 153, 106, 0.18),
        transparent 30%
      ),
      radial-gradient(
        circle at 20% 10%,
        rgba(105, 185, 255, 0.14),
        transparent 26%
      ),
      linear-gradient(
        180deg,
        #0b1721 0%,
        #0d1c27 100%
      );
  }
  
  .hero::after {
    content: "";
  
    position: absolute;
    inset: auto 0 0;
  
    height: 1px;
  
    background: linear-gradient(
      90deg,
      transparent,
      rgba(105, 185, 255, 0.4),
      transparent
    );
  }
  
  .hero-grid {
    display: grid;
    grid-template-columns:
      minmax(0, 0.92fr)
      minmax(420px, 1.08fr);
  
    align-items: center;
  
    gap: 56px;
  }
  
  .hero-lead {
    max-width: 680px;
  
    margin-bottom: 28px;
  
    color: #c2d0d9;
  
    font-size: 18px;
  }
  
  .hero-actions {
    display: flex;
    align-items: center;
    flex-wrap: wrap;
  
    gap: 20px;
  }
  
  .hero-points {
    display: flex;
    flex-wrap: wrap;
  
    gap: 20px;
  
    margin: 30px 0 0;
    padding: 0;
  
    color: #c7d4dc;
  
    font-size: 14px;
  
    list-style: none;
  }
  
  .hero-points li {
    display: inline-flex;
    align-items: center;
    gap: 8px;
  }
  
  .hero-points li::before {
    content: "";
  
    width: 7px;
    height: 7px;
  
    border-radius: 50%;
  
    background: var(--brand);
  
    box-shadow: 0 0 0 5px rgba(105, 185, 255, 0.09);
  }
  
  .hero-visual {
    position: relative;
  }
  
  .hero-frame {
    padding: 12px;
  
    border: 1px solid rgba(157, 199, 225, 0.28);
    border-radius: var(--radius-large);
  
    background: linear-gradient(
      145deg,
      rgba(255, 255, 255, 0.1),
      rgba(255, 255, 255, 0.03)
    );
  
    box-shadow: var(--shadow);
  }
  
  .hero-frame img {
    width: 100%;
    max-height: 500px;
  
    object-fit: contain;
  
    border-radius: 20px;
  }
  
  .download-status {
    position: absolute;
    right: 24px;
    bottom: -22px;
  
    width: min(300px, calc(100% - 40px));
  
    padding: 15px 18px;
  
    color: var(--ink);
    background: rgba(255, 255, 255, 0.95);
  
    border: 1px solid rgba(255, 255, 255, 0.8);
    border-radius: 14px;
  
    box-shadow: 0 18px 40px rgba(0, 0, 0, 0.2);
  }
  
  .download-status span,
  .download-status strong {
    display: block;
  }
  
  .download-status span {
    color: var(--brand-strong);
  
    font-size: 12px;
    font-weight: 900;
  }
  
  .download-status strong {
    margin-top: 2px;
    font-size: 14px;
  }
  
  /* Trust strip */
  
  .trust-strip {
    border-bottom: 1px solid var(--line);
    background: #101f2a;
  }
  
  .trust-grid {
    display: grid;
    grid-template-columns: repeat(3, 1fr);
  }
  
  .trust-grid div {
    display: flex;
    min-height: 74px;
  
    align-items: center;
  
    gap: 12px;
  
    padding: 0 28px;
  
    border-right: 1px solid var(--line);
  }
  
  .trust-grid div:last-child {
    border-right: 0;
  }
  
  .trust-grid span {
    color: var(--brand);
  
    font-size: 13px;
    font-weight: 900;
  }
  
  .trust-grid strong {
    font-size: 14px;
  }
  
  /* Sections */
  
  .section {
    padding: 96px 0;
  }
  
  .section-light {
    color: var(--ink);
    background: #f4f8fb;
  }
  
  .section-dark {
    color: var(--text);
    background: #0f1e29;
  }
  
  .section-heading {
    max-width: 760px;
    margin-bottom: 46px;
  }
  
  .section-heading p:last-child {
    color: var(--ink-soft);
  }
  
  .section-heading.compact {
    margin-bottom: 34px;
  }
  
  .section-heading-light p:last-child {
    color: var(--muted);
  }
  
  /* Device selector */
  
  .device-selector {
    display: grid;
    grid-template-columns:
      minmax(0, 1.12fr)
      minmax(300px, 0.88fr);
  
    gap: 22px;
  }
  
  .device-group {
    overflow: hidden;
  
    border: 1px solid var(--line-light);
    border-radius: 22px;
  
    background: var(--white);
  }
  
  .device-group-head {
    display: flex;
    align-items: center;
  
    gap: 16px;
  
    padding: 24px 26px;
  
    border-bottom: 1px solid var(--line-light);
  
    background: linear-gradient(
      135deg,
      #ffffff,
      #edf7fd
    );
  }
  
  .group-index {
    display: inline-grid;
  
    width: 42px;
    height: 42px;
  
    place-items: center;
  
    color: var(--brand-strong);
    background: var(--brand-soft);
  
    border: 1px solid #cce8fa;
    border-radius: 50%;
  
    font-weight: 900;
  }
  
  .device-group-head h3 {
    margin-bottom: 2px;
  }
  
  .device-group-head p {
    margin: 0;
  
    color: var(--ink-soft);
    font-size: 14px;
  }
  
  .device-links {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
  }
  
  .desktop-group .device-links {
    grid-template-columns: 1fr;
  }
  
  .device-links a {
    display: grid;
    grid-template-columns: auto 1fr auto;
    align-items: center;
  
    gap: 14px;
  
    min-height: 98px;
  
    padding: 20px 22px;
  
    border-right: 1px solid var(--line-light);
    border-bottom: 1px solid var(--line-light);
  
    transition: background 160ms ease;
  }
  
  .device-links a:nth-child(2n) {
    border-right: 0;
  }
  
  .device-links a:hover {
    background: #f5fbff;
  }
  
  .device-code {
    display: inline-grid;
  
    min-width: 42px;
    height: 32px;
  
    place-items: center;
  
    padding-inline: 8px;
  
    color: var(--brand-strong);
    background: var(--brand-soft);
  
    border-radius: 999px;
  
    font-size: 11px;
    font-weight: 900;
  }
  
  .device-links strong,
  .device-links small {
    display: block;
  }
  
  .device-links small {
    margin-top: 4px;
  
    color: var(--ink-soft);
  }
  
  .device-links b {
    color: var(--brand-strong);
    font-size: 13px;
  }
  
  /* Split section */
  
  .split-layout,
  .security-layout {
    display: grid;
    grid-template-columns:
      minmax(0, 0.92fr)
      minmax(0, 1.08fr);
  
    align-items: center;
  
    gap: 64px;
  }
  
  .media-panel,
  .security-visual {
    padding: 24px;
  
    border: 1px solid var(--line);
    border-radius: var(--radius-large);
  
    background: linear-gradient(
      145deg,
      rgba(255, 255, 255, 0.08),
      rgba(255, 255, 255, 0.025)
    );
  }
  
  .media-panel img,
  .security-visual img {
    width: 100%;
    max-height: 520px;
  
    object-fit: contain;
  }
  
  .content-panel > p:not(.eyebrow) {
    color: var(--muted);
  }
  
  .comparison-list {
    margin: 32px 0 0;
  
    border-top: 1px solid var(--line);
  }
  
  .comparison-list div {
    display: grid;
    grid-template-columns: 150px 1fr;
  
    gap: 18px;
  
    padding: 18px 0;
  
    border-bottom: 1px solid var(--line);
  }
  
  .comparison-list dt {
    color: var(--brand);
    font-weight: 850;
  }
  
  .comparison-list dd {
    margin: 0;
    color: #c6d2da;
  }
  
  /* Checklist */
  
  .check-layout {
    display: grid;
    grid-template-columns:
      minmax(260px, 0.78fr)
      minmax(0, 1.22fr);
  
    gap: 60px;
  }
  
  .check-intro {
    position: sticky;
    top: 110px;
  
    align-self: start;
  
    padding-left: 22px;
  
    border-left: 4px solid var(--brand);
  }
  
  .check-intro p {
    color: var(--ink-soft);
  }
  
  .check-list {
    margin: 0;
    padding: 0;
  
    list-style: none;
  
    border-top: 1px solid var(--line-light);
  }
  
  .check-list li {
    display: grid;
    grid-template-columns: 56px 1fr;
  
    gap: 18px;
  
    padding: 22px 0;
  
    border-bottom: 1px solid var(--line-light);
  }
  
  .check-list li > span {
    color: var(--brand-strong);
    font-weight: 950;
  }
  
  .check-list strong {
    display: block;
    margin-bottom: 4px;
  }
  
  .check-list p {
    margin: 0;
  
    color: var(--ink-soft);
  }
  
  /* Flow */
  
  .section-flow {
    background:
      linear-gradient(
        180deg,
        rgba(15, 30, 41, 0.98),
        rgba(15, 30, 41, 0.98)
      ),
      radial-gradient(
        circle at top right,
        rgba(105, 185, 255, 0.18),
        transparent 30%
      );
  }
  
  .flow-grid {
    display: grid;
    grid-template-columns:
      minmax(0, 0.9fr)
      minmax(360px, 1.1fr);
  
    gap: 56px;
  }
  
  .flow-steps {
    position: relative;
  }
  
  .flow-steps::before {
    content: "";
  
    position: absolute;
    top: 14px;
    bottom: 14px;
    left: 19px;
  
    width: 1px;
  
    background: linear-gradient(
      var(--brand),
      rgba(105, 185, 255, 0.08)
    );
  }
  
  .flow-steps article {
    position: relative;
  
    display: grid;
    grid-template-columns: 40px 1fr;
  
    gap: 18px;
  
    padding-bottom: 30px;
  }
  
  .flow-steps article > span {
    position: relative;
    z-index: 1;
  
    display: grid;
  
    width: 40px;
    height: 40px;
  
    place-items: center;
  
    color: #07131b;
    background: var(--brand);
  
    border-radius: 50%;
  
    font-size: 12px;
    font-weight: 950;
  }
  
  .flow-steps h3 {
    margin: 4px 0 6px;
  }
  
  .flow-steps p {
    margin: 0;
    color: var(--muted);
  }
  
  .flow-media {
    display: grid;
    gap: 18px;
  }
  
  .flow-media figure {
    margin: 0;
    overflow: hidden;
  
    border: 1px solid var(--line);
    border-radius: 20px;
  
    background: rgba(255, 255, 255, 0.04);
  }
  
  .flow-media img {
    width: 100%;
    max-height: 300px;
  
    object-fit: contain;
  
    background: #0b1721;
  }
  
  .flow-media figcaption {
    padding: 12px 16px;
  
    color: #bfced8;
  
    font-size: 13px;
  }
  
  /* Security */
  
  .security-layout {
    grid-template-columns:
      minmax(0, 1fr)
      minmax(340px, 0.9fr);
  }
  
  .security-content > p:not(.eyebrow) {
    color: var(--ink-soft);
  }
  
  .security-list {
    margin: 28px 0 0;
    padding: 0;
  
    list-style: none;
  }
  
  .security-list li {
    position: relative;
  
    padding: 12px 0 12px 28px;
  
    border-bottom: 1px solid var(--line-light);
  }
  
  .security-list li::before {
    content: "✓";
  
    position: absolute;
    left: 0;
  
    color: var(--brand-strong);
  
    font-weight: 950;
  }
  
  .security-visual {
    background: var(--white);
    border-color: var(--line-light);
  }
  
  /* FAQ */
  
  .faq-layout {
    display: grid;
    grid-template-columns:
      minmax(260px, 0.72fr)
      minmax(0, 1.28fr);
  
    gap: 56px;
  }
  
  .faq-list {
    border-top: 1px solid var(--line);
  }
  
  .faq-list details {
    border-bottom: 1px solid var(--line);
  }
  
  .faq-list summary {
    position: relative;
  
    padding: 22px 48px 22px 0;
  
    color: var(--white);
  
    cursor: pointer;
  
    font-weight: 800;
  
    list-style: none;
  }
  
  .faq-list summary::-webkit-details-marker {
    display: none;
  }
  
  .faq-list summary::after {
    content: "+";
  
    position: absolute;
    top: 20px;
    right: 4px;
  
    color: var(--brand);
  
    font-size: 24px;
    line-height: 1;
  }
  
  .faq-list details[open] summary::after {
    content: "−";
  }
  
  .faq-list details p {
    margin: 0;
  
    padding: 0 42px 22px 0;
  
    color: var(--muted);
  }
  
  /* Related links */
  
  .related-directory {
    display: grid;
    grid-template-columns:
      0.8fr
      1.2fr
      1fr
      1fr;
  
    gap: 18px;
  }
  
  .related-directory > div {
    padding: 24px;
  
    border-top: 3px solid var(--brand);
  
    background: var(--white);
  
    box-shadow: 0 12px 34px rgba(14, 42, 59, 0.07);
  }
  
  .related-directory h3 {
    margin-bottom: 18px;
    font-size: 17px;
  }
  
  .related-directory a {
    display: block;
  
    padding: 9px 0;
  
    color: var(--ink-soft);
  
    border-bottom: 1px solid #edf2f5;
  }
  
  .related-directory a:hover {
    color: var(--brand-strong);
  }
  
  /* Bottom CTA */
  
  .bottom-cta {
    color: var(--ink);
  
    background: linear-gradient(
      135deg,
      #dff2ff,
      #f7fbfe
    );
  
    border-top: 1px solid #c9e5f5;
  }
  
  .bottom-cta-inner {
    display: flex;
    min-height: 230px;
  
    align-items: center;
    justify-content: space-between;
  
    gap: 40px;
  }
  
  .bottom-cta h2 {
    max-width: 760px;
    margin-bottom: 8px;
  }
  
  .bottom-cta p:not(.eyebrow) {
    margin-bottom: 0;
    color: var(--ink-soft);
  }
  
  .bottom-cta-actions {
    display: flex;
    align-items: center;
  
    gap: 18px;
  
    flex-shrink: 0;
  }
  
  .text-link-dark {
    color: var(--brand-strong);
  }
  
  /* Footer */
  
  .site-footer {
    padding: 34px 0;
  
    color: #a9bbc7;
    background: #09141c;
  
    border-top: 1px solid var(--line);
  }
  
  .footer-grid {
    display: grid;
    grid-template-columns:
      0.7fr
      1.6fr
      0.7fr;
  
    align-items: center;
  
    gap: 32px;
  }
  
  .footer-grid img {
    width: 120px;
    margin-bottom: 10px;
  }
  
  .footer-grid p {
    margin: 0;
    font-size: 13px;
  }
  
  .footer-grid p:last-child {
    text-align: right;
  }
  
  /* Back to top */
  
  .back-to-top {
    position: fixed;
    right: 22px;
    bottom: 22px;
    z-index: 40;
  
    width: 44px;
    height: 44px;
  
    color: #08151d;
    background: var(--brand);
  
    border: 0;
    border-radius: 50%;
  
    box-shadow: 0 14px 34px rgba(0, 0, 0, 0.25);
  
    cursor: pointer;
  
    opacity: 0;
    pointer-events: none;
  
    transform: translateY(10px);
  
    transition:
      opacity 160ms ease,
      transform 160ms ease;
  }
  
  .back-to-top.is-visible {
    opacity: 1;
    pointer-events: auto;
  
    transform: translateY(0);
  }
  
  /* Tablet */
  
  @media (max-width: 980px) {
    .desktop-nav {
      display: none;
    }
  
    .hero-grid,
    .split-layout,
    .security-layout,
    .flow-grid,
    .faq-layout {
      grid-template-columns: 1fr;
    }
  
    .hero-grid {
      gap: 42px;
    }
  
    .hero-copy,
    .hero-visual {
      max-width: 760px;
    }
  
    .device-selector {
      grid-template-columns: 1fr;
    }
  
    .split-layout .media-panel {
      order: 2;
    }
  
    .check-layout {
      grid-template-columns: 1fr;
      gap: 34px;
    }
  
    .check-intro {
      position: static;
    }
  
    .related-directory {
      grid-template-columns: repeat(2, 1fr);
    }
  
    .bottom-cta-inner {
      align-items: flex-start;
      flex-direction: column;
      justify-content: center;
  
      padding-block: 48px;
    }
  
    .footer-grid {
      grid-template-columns: 1fr;
    }
  
    .footer-grid p:last-child {
      text-align: left;
    }
  }
  
  /* Mobile */
  
  @media (max-width: 780px) {
    .container {
      width: min(calc(100% - 32px), var(--container));
    }
  
    .nav-shell {
      min-height: 64px;
      gap: 16px;
    }
  
    .brand img {
      width: 108px;
    }
  
    .button-small {
      min-height: 38px;
      padding-inline: 12px;
      font-size: 12px;
    }
  
    .hero {
      padding: 54px 0 44px;
    }
  
    h1 {
      font-size: clamp(38px, 12vw, 54px);
    }
  
    .trust-grid {
      grid-template-columns: 1fr;
    }
  
    .trust-grid div {
      min-height: 58px;
  
      border-right: 0;
      border-bottom: 1px solid var(--line);
    }
  
    .section {
      padding: 72px 0;
    }
  
    .device-links {
      grid-template-columns: 1fr;
    }
  
    .device-links a {
      border-right: 0;
    }
  
    .comparison-list div {
      grid-template-columns: 1fr;
      gap: 6px;
    }
  
    .flow-grid {
      gap: 34px;
    }
  
    .related-directory {
      grid-template-columns: 1fr;
    }
  
    .bottom-cta-actions {
      align-items: flex-start;
      flex-direction: column;
    }
  }
  
  @media (max-width: 520px) {
    .container {
      width: min(calc(100% - 24px), var(--container));
    }
  
    .nav-shell {
      grid-template-columns: 1fr auto;
    }
  
    .hero-lead {
      font-size: 16px;
    }
  
    .hero-actions {
      align-items: stretch;
      flex-direction: column;
    }
  
    .hero-actions .button {
      width: 100%;
    }
  
    .hero-points {
      gap: 10px 16px;
    }
  
    .download-status {
      position: static;
  
      width: 100%;
  
      margin-top: 12px;
    }
  
    .device-group-head,
    .device-links a,
    .related-directory > div {
      padding-inline: 18px;
    }
  
    .device-links a {
      grid-template-columns: auto 1fr;
    }
  
    .device-links b {
      grid-column: 2;
    }
  
    .media-panel,
    .security-visual {
      padding: 14px;
    }
  
    .check-list li {
      grid-template-columns: 42px 1fr;
    }
  
    .faq-list summary {
      padding-right: 36px;
    }
  
    .faq-list details p {
      padding-right: 0;
    }
  
    .bottom-cta-inner {
      min-height: 0;
    }
  }
  
  @media (prefers-reduced-motion: reduce) {
    *,
    *::before,
    *::after {
      scroll-behavior: auto !important;
      transition: none !important;
    }
  }