:root {
  --ink: #07162d;
  --ink-soft: #27364b;
  --muted: #667284;
  --teal: #2f9693;
  --teal-dark: #247a78;
  --teal-pale: #e7f4f3;
  --line: #a9c2c4;
  --paper: #ffffff;
  --mist: #f5f8f8;
  --max: 1120px;
  --serif: Georgia, "Times New Roman", "Songti SC", STSong, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  background: var(--paper);
  font-family: var(--sans);
  font-size: 17px;
  line-height: 1.7;
  text-rendering: optimizeLegibility;
}

a {
  color: var(--teal-dark);
  text-decoration-thickness: 1px;
  text-underline-offset: 0.2em;
}

a:hover {
  color: var(--ink);
}

button,
summary {
  font: inherit;
}

:focus-visible {
  outline: 3px solid var(--teal);
  outline-offset: 4px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  color: var(--paper);
  background: var(--ink);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.site-shell {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.site-header {
  border-bottom: 2px solid var(--ink);
  background: rgba(255, 255, 255, 0.98);
}

.header-inner {
  width: min(calc(100% - 48px), var(--max));
  min-height: 74px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 28px;
}

.brand {
  color: var(--ink);
  font-family: var(--serif);
  font-size: clamp(1.25rem, 2vw, 1.6rem);
  font-weight: 700;
  text-decoration: none;
  white-space: nowrap;
}

.desktop-nav {
  display: flex;
  align-items: center;
  gap: 24px;
}

.desktop-nav > a {
  color: var(--ink);
  font-family: var(--serif);
  font-size: 1.05rem;
  text-decoration: none;
}

.desktop-nav > a[aria-current="page"] {
  color: var(--teal-dark);
  text-decoration: underline;
  text-decoration-color: var(--teal);
}

.language-switch {
  display: inline-flex;
  align-items: center;
  padding-left: 18px;
  border-left: 1px solid var(--line);
}

.language-switch button {
  padding: 4px 7px;
  color: var(--ink);
  background: transparent;
  border: 0;
  border-bottom: 2px solid transparent;
  cursor: pointer;
}

.language-switch button.is-active {
  color: var(--teal-dark);
  border-bottom-color: var(--teal);
}

.language-separator {
  color: var(--muted);
}

.mobile-menu {
  display: none;
  position: relative;
}

.mobile-menu summary {
  width: 44px;
  height: 44px;
  display: grid;
  place-items: center;
  list-style: none;
  cursor: pointer;
}

.mobile-menu summary::-webkit-details-marker {
  display: none;
}

.menu-icon,
.menu-icon::before,
.menu-icon::after {
  width: 24px;
  height: 2px;
  display: block;
  background: var(--ink);
  content: "";
}

.menu-icon {
  position: relative;
}

.menu-icon::before {
  position: absolute;
  top: -7px;
}

.menu-icon::after {
  position: absolute;
  top: 7px;
}

.mobile-menu-panel {
  position: absolute;
  z-index: 20;
  top: 50px;
  right: 0;
  min-width: 240px;
  padding: 18px;
  display: grid;
  gap: 12px;
  background: var(--paper);
  border: 1px solid var(--line);
  box-shadow: 0 18px 50px rgba(7, 22, 45, 0.14);
}

.mobile-menu-panel a {
  color: var(--ink);
  text-decoration: none;
}

main:focus {
  outline: none;
}

.page-main {
  flex: 1;
}

.home-main {
  width: min(calc(100% - 48px), 900px);
  margin: 0 auto;
  padding: clamp(76px, 11vw, 128px) 0 80px;
}

.home-title {
  max-width: 900px;
  margin: 0 0 42px;
  font-family: var(--serif);
  font-size: clamp(2.8rem, 5vw, 3.85rem);
  font-weight: 500;
  line-height: 1.04;
  letter-spacing: -0.04em;
}

.home-links {
  margin: 0 0 52px;
  border-top: 1px solid var(--ink-soft);
}

.home-link {
  min-height: 68px;
  padding: 12px 14px 12px 18px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  color: var(--ink);
  border-bottom: 1px solid var(--ink-soft);
  border-left: 4px solid var(--teal);
  font-family: var(--serif);
  font-size: clamp(1.4rem, 3vw, 1.8rem);
  text-decoration: none;
  transition: padding 160ms ease, color 160ms ease, background 160ms ease;
}

.home-link:hover {
  padding-left: 26px;
  color: var(--ink);
  background: var(--mist);
}

.arrow-icon {
  width: 24px;
  height: 24px;
  flex: 0 0 auto;
}

.product-note {
  padding: 0 0 0 18px;
  border-left: 4px solid var(--teal);
}

.product-note h2 {
  margin: 0 0 4px;
  font-family: var(--serif);
  font-size: 1.45rem;
}

.product-note p {
  max-width: 760px;
  margin: 0;
  color: var(--ink-soft);
}

.site-footer {
  border-top: 1px solid var(--line);
}

.footer-inner {
  width: min(calc(100% - 48px), var(--max));
  min-height: 68px;
  margin: 0 auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  color: var(--muted);
  font-size: 0.88rem;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  gap: 18px;
}

.footer-links a {
  color: var(--ink-soft);
}

.document-hero {
  padding: 54px 0 30px;
  border-bottom: 1px solid var(--line);
}

.document-hero-inner,
.support-main {
  width: min(calc(100% - 48px), var(--max));
  margin: 0 auto;
}

.document-hero h1,
.support-main h1 {
  margin: 0;
  font-size: clamp(2.6rem, 6vw, 4.5rem);
  line-height: 1.05;
  letter-spacing: -0.045em;
}

.document-meta {
  margin-top: 20px;
  padding-top: 16px;
  display: flex;
  flex-wrap: wrap;
  gap: 10px 24px;
  color: var(--ink-soft);
  border-top: 2px solid var(--teal);
  font-size: 0.95rem;
}

.document-layout {
  width: min(100%, 1480px);
  margin: 0 auto;
  display: grid;
  grid-template-columns: minmax(210px, 260px) minmax(0, 920px);
  justify-content: center;
}

.document-toc {
  padding: 44px 28px;
  align-self: start;
  position: sticky;
  top: 0;
  border-right: 1px solid var(--line);
}

.document-toc strong {
  display: block;
  margin-bottom: 14px;
  color: var(--teal-dark);
  font-size: 0.86rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.document-toc a {
  display: block;
  margin: 0 0 11px;
  color: var(--ink-soft);
  font-size: 0.9rem;
  line-height: 1.35;
  text-decoration: none;
}

.document-toc a:hover {
  color: var(--teal-dark);
}

.document-content {
  min-width: 0;
  padding: 48px clamp(28px, 6vw, 72px) 92px;
}

.content-section {
  padding: 0 0 30px;
  margin: 0 0 34px;
  border-bottom: 1px solid var(--line);
}

.content-section:last-child {
  border-bottom: 0;
}

.content-section h2 {
  margin: 0 0 16px;
  font-size: clamp(1.55rem, 3vw, 2rem);
  line-height: 1.18;
}

.content-section h3 {
  margin: 26px 0 10px;
  font-size: 1.16rem;
  line-height: 1.35;
}

.content-section p,
.content-section ul,
.content-section ol {
  margin-top: 0;
}

.content-section li + li {
  margin-top: 8px;
}

.product-disclosure {
  margin-top: 54px;
  padding-top: 28px;
  border-top: 4px solid var(--teal);
}

.product-disclosure > h2 {
  font-size: clamp(2rem, 4vw, 3rem);
  letter-spacing: -0.035em;
}

.retention-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1px;
  margin: 24px 0;
  background: var(--line);
  border: 1px solid var(--line);
}

.retention-item {
  padding: 20px;
  background: var(--paper);
}

.retention-item strong {
  display: block;
  margin-bottom: 6px;
  color: var(--teal-dark);
}

.callout {
  margin: 24px 0;
  padding: 18px 20px;
  background: var(--teal-pale);
  border-left: 4px solid var(--teal);
}

.support-main {
  padding: clamp(54px, 8vw, 90px) 0 92px;
}

.support-contact {
  margin: 22px 0 30px;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  font-size: 1.12rem;
  text-decoration: none;
}

.mail-icon {
  width: 25px;
  height: 25px;
  color: var(--ink);
}

.topic-nav {
  margin: 0 0 18px;
  padding: 16px 0;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 0;
  border-top: 1px solid var(--teal);
  border-bottom: 1px solid var(--teal);
}

.topic-nav a {
  padding: 0 18px;
  color: var(--ink);
  border-right: 1px solid var(--teal);
  text-decoration: none;
}

.topic-nav a:first-child {
  padding-left: 0;
  color: var(--teal-dark);
}

.topic-nav a:last-child {
  border-right: 0;
}

.support-section {
  padding: 24px 0 28px;
  border-bottom: 1px solid var(--teal);
}

.support-section:last-child {
  border-bottom: 0;
}

.support-section h2 {
  margin: 0 0 10px;
  font-size: clamp(1.5rem, 3vw, 2rem);
  line-height: 1.2;
}

.support-section p,
.support-section ul,
.support-section ol {
  margin-top: 0;
}

.support-section li + li {
  margin-top: 7px;
}

code {
  padding: 0.12em 0.34em;
  background: var(--mist);
  border: 1px solid #dae4e5;
  border-radius: 4px;
  color: var(--ink-soft);
  font-size: 0.88em;
  overflow-wrap: anywhere;
}

html[data-language="en"] .lang-zh,
html[data-language="zh"] .lang-en {
  display: none !important;
}

@media (max-width: 820px) {
  body {
    font-size: 16px;
    line-height: 1.62;
  }

  .header-inner,
  .document-hero-inner,
  .support-main,
  .footer-inner,
  .home-main {
    width: min(calc(100% - 36px), var(--max));
  }

  .desktop-nav {
    display: none;
  }

  .mobile-menu {
    display: block;
  }

  .brand {
    color: var(--teal-dark);
    font-family: var(--sans);
  }

  .home-main {
    padding-top: 62px;
  }

  .home-title {
    font-size: clamp(2.65rem, 13vw, 4rem);
  }

  .document-layout {
    display: block;
  }

  .document-toc {
    display: none;
  }

  .document-content {
    padding: 34px 18px 72px;
  }

  .retention-grid {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    padding: 18px 0;
    align-items: flex-start;
    flex-direction: column;
  }

  .topic-nav {
    gap: 8px 14px;
  }

  .topic-nav a,
  .topic-nav a:first-child {
    padding: 0;
    border-right: 0;
  }
}

@media (max-width: 480px) {
  .header-inner {
    min-height: 66px;
  }

  .brand {
    font-size: 1.18rem;
  }

  .home-main {
    padding-bottom: 58px;
  }

  .home-title,
  .document-hero h1,
  .support-main h1 {
    overflow-wrap: anywhere;
  }

  .document-hero {
    padding-top: 38px;
  }

  .support-main {
    padding-top: 48px;
  }

  .mobile-menu-panel {
    right: -4px;
    width: min(280px, calc(100vw - 28px));
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  .home-link {
    transition: none;
  }
}

@media print {
  .site-header,
  .site-footer,
  .document-toc,
  .topic-nav,
  .skip-link {
    display: none !important;
  }

  body {
    color: #000;
    font-size: 11pt;
  }

  .document-content,
  .support-main {
    width: 100%;
    padding: 0;
  }

  a {
    color: #000;
  }
}