:root {
  --paper: #fffdf9;
  --surface: #ffffff;
  --soft: #f7fafd;
  --warm: #fff8f3;
  --ink: #0b2c4d;
  --text: #324f6a;
  --muted: #6f8295;
  --line: #dce5ed;
  --line-strong: #c4d3e1;
  --accent: #ff6b5d;
  --accent-strong: #e85b51;
  --link: #2477d4;
  --serif: "Songti SC", STSong, SimSun, "Noto Serif CJK SC", Georgia, serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  --container: 1180px;
  --header-height: 76px;
}

* { box-sizing: border-box; }

html { scroll-behavior: smooth; }

body {
  margin: 0;
  min-width: 320px;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

body.menu-open { overflow: hidden; }

img { max-width: 100%; }

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

button { font: inherit; }

p, h1, h2, h3, dl, dd, blockquote { margin-top: 0; }

.skip-link {
  position: fixed;
  left: 16px;
  top: -80px;
  z-index: 100;
  padding: 10px 16px;
  background: var(--ink);
  color: white;
}

.skip-link:focus { top: 12px; }

:focus-visible { outline: 3px solid rgba(36, 119, 212, .5); outline-offset: 3px; }

.container {
  width: min(calc(100% - 48px), var(--container));
  margin-inline: auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  min-height: var(--header-height);
  border-bottom: 1px solid rgba(220, 229, 237, .9);
  background: rgba(255, 253, 249, .96);
  backdrop-filter: blur(16px);
}

.nav-shell {
  width: min(calc(100% - 48px), 1280px);
  min-height: var(--header-height);
  margin-inline: auto;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 32px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 11px;
  flex: 0 0 auto;
}

.brand-mark {
  width: 38px;
  height: 38px;
  display: block;
  border-radius: 8px;
}

.brand-name {
  font-family: Georgia, "Times New Roman", serif;
  font-size: 22px;
  font-weight: 600;
  letter-spacing: -.01em;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: clamp(18px, 2vw, 30px);
  color: var(--text);
  font-size: 14px;
  font-weight: 600;
}

.site-nav a { transition: color .18s ease; }
.site-nav a:hover { color: var(--accent-strong); }

.site-nav .language-link {
  padding-left: clamp(18px, 2vw, 30px);
  border-left: 1px solid var(--line);
  color: var(--muted);
}

.nav-download {
  min-height: 40px;
  padding: 7px 18px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid var(--ink);
  border-radius: 7px;
  color: var(--ink);
}

.site-nav .nav-download:hover { background: var(--ink); color: white; }

.menu-button {
  display: none;
  min-height: 42px;
  padding: 6px 12px;
  border: 1px solid var(--line-strong);
  border-radius: 6px;
  background: transparent;
  color: var(--ink);
  cursor: pointer;
}

.hero {
  min-height: 680px;
  padding: clamp(92px, 10vw, 148px) 0 clamp(92px, 10vw, 132px);
  border-bottom: 1px solid var(--line);
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(360px, .65fr);
  align-items: center;
  gap: clamp(64px, 9vw, 128px);
}

.eyebrow,
.summary-kicker,
.feature-index {
  margin-bottom: 18px;
  color: var(--accent-strong);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: .14em;
  line-height: 1.4;
  text-transform: uppercase;
}

h1, h2 {
  font-family: var(--serif);
  font-weight: 400;
  letter-spacing: -.035em;
}

h1 {
  max-width: 820px;
  margin-bottom: 30px;
  font-size: clamp(48px, 5.5vw, 78px);
  line-height: 1.13;
}

h2 {
  margin-bottom: 20px;
  font-size: clamp(34px, 4vw, 54px);
  line-height: 1.18;
}

h3 {
  margin-bottom: 10px;
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 500;
  line-height: 1.35;
}

.hero-lead {
  max-width: 720px;
  margin-bottom: 34px;
  color: var(--text);
  font-size: clamp(18px, 1.5vw, 21px);
  line-height: 1.8;
}

.hero-actions { display: flex; flex-wrap: wrap; gap: 12px; }

.button {
  min-height: 50px;
  padding: 12px 22px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border: 1px solid transparent;
  border-radius: 7px;
  font-size: 15px;
  font-weight: 700;
  line-height: 1.4;
  transition: background .18s ease, border-color .18s ease, color .18s ease, transform .18s ease;
}

.button:hover { transform: translateY(-1px); }
.button-primary { background: var(--accent); color: white; }
.button-primary:hover { background: var(--accent-strong); }
.button-secondary { border-color: var(--line-strong); background: transparent; color: var(--ink); }
.button-secondary:hover { border-color: var(--ink); }

.hero-note {
  margin: 22px 0 0;
  color: var(--muted);
  font-size: 13px;
}

.product-summary {
  padding: 32px 0 10px;
  border-top: 2px solid var(--ink);
  border-bottom: 1px solid var(--line-strong);
}

.product-summary h2 { margin-bottom: 28px; font-size: 34px; }
.product-summary dl { margin-bottom: 0; }

.product-summary dl div {
  padding: 15px 0;
  display: grid;
  grid-template-columns: 98px minmax(0, 1fr);
  gap: 18px;
  border-top: 1px solid var(--line);
}

.product-summary dt { color: var(--muted); font-size: 13px; }
.product-summary dd { margin: 0; color: var(--ink); font-size: 14px; font-weight: 600; }

.definition { padding: 44px 0; background: var(--ink); color: white; }

.definition-grid {
  display: grid;
  grid-template-columns: minmax(260px, .72fr) minmax(0, 1.28fr);
  align-items: start;
  gap: clamp(42px, 8vw, 118px);
}

.definition h2 { margin: 0; color: white; font-size: 32px; }
.definition p { margin: 0; color: #dce5ed; font-size: 18px; line-height: 1.8; }
.definition strong { color: white; }

.section { padding: clamp(92px, 10vw, 142px) 0; }
.section-muted { border-block: 1px solid var(--line); background: var(--soft); }

.section-head { max-width: 760px; margin-bottom: 56px; }
.section-head > p:not(.eyebrow) { max-width: 660px; margin-bottom: 0; color: var(--muted); font-size: 17px; }

.process-list { margin: 0; padding: 0; list-style: none; border-top: 1px solid var(--line-strong); }

.process-list li {
  padding: 28px 0;
  display: grid;
  grid-template-columns: 130px minmax(0, 1fr);
  align-items: start;
  gap: 28px;
  border-bottom: 1px solid var(--line);
}

.process-list li > span {
  color: var(--accent-strong);
  font-size: 13px;
  font-weight: 800;
  letter-spacing: .1em;
}

.process-list li div { display: grid; grid-template-columns: minmax(210px, .5fr) minmax(0, 1fr); gap: 48px; }
.process-list h3, .process-list p { margin: 0; }
.process-list p { color: var(--muted); }

.split-head {
  display: grid;
  grid-template-columns: minmax(0, 1.2fr) minmax(280px, .8fr);
  align-items: end;
  gap: 72px;
}

.split-head .section-head { margin-bottom: 48px; }
.section-aside { margin-bottom: 56px; color: var(--muted); }

.feature-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  border-top: 1px solid var(--line-strong);
  border-bottom: 1px solid var(--line-strong);
}

.feature-grid article { min-height: 280px; padding: 30px 28px; border-right: 1px solid var(--line); }
.feature-grid article:first-child { padding-left: 0; }
.feature-grid article:last-child { padding-right: 0; border-right: 0; }
.feature-grid h3 { margin-top: 72px; }
.feature-grid article > p:last-child { margin-bottom: 0; color: var(--muted); }

.use-case-grid,
.faq-grid {
  display: grid;
  grid-template-columns: minmax(280px, .72fr) minmax(0, 1.28fr);
  align-items: start;
  gap: clamp(64px, 9vw, 130px);
}

.sticky-head { position: sticky; top: calc(var(--header-height) + 42px); margin-bottom: 0; }
.query-list { border-top: 1px solid var(--line-strong); }
.query-list article { padding: 28px 0; border-bottom: 1px solid var(--line); }
.query-list h3 { margin-bottom: 7px; }
.query-list p { margin-bottom: 14px; color: var(--text); }
.query-list span { color: var(--muted); font-size: 13px; }

.comparison { background: var(--warm); }
.comparison-table { border-top: 2px solid var(--ink); }

.table-row {
  min-height: 68px;
  display: grid;
  grid-template-columns: .6fr 1.2fr 1fr;
  align-items: center;
  gap: 32px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line-strong);
}

.table-head { color: var(--muted); font-size: 12px; font-weight: 800; letter-spacing: .08em; text-transform: uppercase; }
.table-row b { font-family: var(--serif); font-size: 19px; font-weight: 500; }
.table-row span { color: var(--text); }

.safety-grid {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(380px, 1fr);
  gap: 86px;
}

.safety-grid .section-head { margin-bottom: 0; }
.safety-copy { border-top: 1px solid var(--line-strong); }
.safety-copy p { margin: 0; padding: 20px 0; border-bottom: 1px solid var(--line); color: var(--text); }

.faq-list { border-top: 2px solid var(--ink); }
.faq-item { border-bottom: 1px solid var(--line); }
.faq-item h3 { margin: 0; font-family: var(--sans); }

.faq-question {
  width: 100%;
  min-height: 76px;
  padding: 20px 56px 20px 0;
  position: relative;
  border: 0;
  background: transparent;
  color: var(--ink);
  text-align: left;
  font-family: var(--serif);
  font-size: 21px;
  font-weight: 500;
  line-height: 1.45;
  cursor: pointer;
}

.faq-question::after {
  content: "Show";
  position: absolute;
  right: 0;
  top: 50%;
  transform: translateY(-50%);
  color: var(--muted);
  font-family: var(--sans);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .08em;
  text-transform: uppercase;
}

html[lang="zh-CN"] .faq-question::after { content: "展开"; }
.faq-question[aria-expanded="true"]::after { content: "Hide"; }
html[lang="zh-CN"] .faq-question[aria-expanded="true"]::after { content: "收起"; }

.faq-answer { display: none; padding: 0 54px 23px 0; }
.faq-answer.is-open { display: block; }
.faq-answer p { margin: 0; color: var(--muted); }

.entity-section { padding: clamp(72px, 8vw, 108px) 0; background: var(--ink); color: white; }

.entity-grid {
  display: grid;
  grid-template-columns: minmax(280px, .72fr) minmax(0, 1.28fr);
  gap: clamp(64px, 9vw, 130px);
}

.entity-section .eyebrow { color: #ff887d; }
.entity-section h2 { color: white; }
.entity-facts { margin: 0; border-top: 1px solid #526b83; }
.entity-facts div { padding: 16px 0; display: grid; grid-template-columns: 150px minmax(0, 1fr); gap: 24px; border-bottom: 1px solid #3a566f; }
.entity-facts dt { color: #93a6b8; font-size: 13px; }
.entity-facts dd { margin: 0; color: white; }

.final-cta { padding: clamp(78px, 9vw, 124px) 0; border-bottom: 1px solid var(--line); }
.final-grid { display: grid; grid-template-columns: minmax(0, 1fr) minmax(320px, .7fr); align-items: end; gap: 84px; }
.final-grid h2 { margin: 0; }
.final-grid > div:last-child { padding-bottom: 8px; }
.final-grid > div:last-child p { color: var(--muted); }

.site-footer { padding: 58px 0 24px; background: var(--surface); }
.footer-grid { display: grid; grid-template-columns: 1fr 1.6fr; gap: 72px; }
.footer-brand p { margin: 16px 0 0; color: var(--muted); }
.footer-grid nav { display: flex; flex-wrap: wrap; justify-content: flex-end; align-content: flex-start; gap: 14px 28px; color: var(--text); font-size: 14px; }
.footer-grid nav a:hover { color: var(--accent-strong); }
.footer-bottom { margin-top: 52px; padding-top: 20px; display: flex; justify-content: space-between; gap: 24px; border-top: 1px solid var(--line); color: var(--muted); font-size: 12px; }

.download-dialog {
  width: min(calc(100% - 32px), 650px);
  padding: 0;
  border: 1px solid var(--line-strong);
  border-radius: 10px;
  background: var(--paper);
  color: var(--ink);
}

.download-dialog::backdrop { background: rgba(15, 31, 48, .52); }
.dialog-inner { padding: clamp(28px, 5vw, 46px); }
.dialog-head { display: flex; align-items: flex-start; justify-content: space-between; gap: 24px; }
.dialog-head h2 { margin-bottom: 18px; font-size: 38px; }
.dialog-close { min-height: 40px; padding: 6px 12px; border: 1px solid var(--line-strong); border-radius: 6px; background: transparent; color: var(--ink); cursor: pointer; }
.dialog-copy { color: var(--muted); }
.store-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 24px; }
.store-link { min-height: 108px; padding: 20px; display: flex; flex-direction: column; justify-content: center; border: 1px solid var(--line-strong); border-radius: 8px; background: white; }
.store-link:hover { border-color: var(--accent); }
.store-link b { font-family: var(--serif); font-size: 21px; font-weight: 500; }
.store-link span { margin-top: 5px; color: var(--muted); font-size: 13px; }

@media (max-width: 980px) {
  .site-nav { gap: 16px; }
  .hero-grid { grid-template-columns: 1fr; }
  .hero-copy { max-width: 800px; }
  .product-summary { max-width: 760px; }
  .feature-grid { grid-template-columns: repeat(2, minmax(0, 1fr)); }
  .feature-grid article { border-bottom: 1px solid var(--line); }
  .feature-grid article:nth-child(2) { border-right: 0; padding-right: 0; }
  .feature-grid article:nth-child(3) { padding-left: 0; border-bottom: 0; }
  .feature-grid article:nth-child(4) { border-bottom: 0; }
  .split-head { grid-template-columns: 1fr; gap: 0; }
  .section-aside { max-width: 680px; }
}

@media (max-width: 820px) {
  :root { --header-height: 68px; }
  .container, .nav-shell { width: min(calc(100% - 32px), var(--container)); }
  .menu-button { display: inline-flex; align-items: center; }
  .site-nav {
    position: fixed;
    left: 0;
    right: 0;
    top: var(--header-height);
    height: calc(100dvh - var(--header-height));
    padding: 34px 24px;
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    background: var(--paper);
    font-size: 19px;
  }
  .site-nav.is-open { display: flex; }
  .site-nav a { padding: 14px 0; border-bottom: 1px solid var(--line); }
  .site-nav .language-link { padding-left: 0; border-left: 0; }
  .site-nav .nav-download { margin-top: 20px; padding: 12px 18px; border: 0; background: var(--accent); color: white; }
  .definition-grid, .use-case-grid, .faq-grid, .entity-grid, .safety-grid, .final-grid { grid-template-columns: 1fr; gap: 44px; }
  .sticky-head { position: static; }
  .process-list li { grid-template-columns: 70px minmax(0, 1fr); }
  .process-list li div { grid-template-columns: 1fr; gap: 8px; }
  .section-head { margin-bottom: 42px; }
  .table-row { grid-template-columns: .7fr 1.3fr; gap: 20px; }
  .table-row > :last-child { grid-column: 2; }
  .table-row.table-head > :last-child { display: none; }
  .footer-grid { grid-template-columns: 1fr; }
  .footer-grid nav { justify-content: flex-start; }
}

@media (max-width: 560px) {
  body { font-size: 15px; }
  .brand-name { font-size: 20px; }
  .brand-mark { width: 34px; height: 34px; }
  .hero { min-height: auto; padding: 72px 0 78px; }
  .hero-grid { gap: 64px; }
  h1 { font-size: clamp(42px, 13vw, 58px); line-height: 1.16; }
  h2 { font-size: 36px; }
  .hero-lead { font-size: 17px; line-height: 1.75; }
  .hero-actions { flex-direction: column; }
  .button { width: 100%; }
  .product-summary dl div { grid-template-columns: 82px minmax(0, 1fr); gap: 14px; }
  .definition { padding: 36px 0; }
  .definition-grid { gap: 20px; }
  .definition h2 { font-size: 28px; }
  .definition p { font-size: 16px; }
  .section { padding: 82px 0; }
  .process-list li { grid-template-columns: 48px minmax(0, 1fr); gap: 16px; }
  .feature-grid { grid-template-columns: 1fr; }
  .feature-grid article, .feature-grid article:first-child, .feature-grid article:nth-child(2), .feature-grid article:nth-child(3), .feature-grid article:nth-child(4) { min-height: 0; padding: 30px 0; border-right: 0; border-bottom: 1px solid var(--line); }
  .feature-grid article:last-child { border-bottom: 0; }
  .feature-grid h3 { margin-top: 36px; }
  .table-row { grid-template-columns: 1fr; gap: 5px; padding: 18px 0; }
  .table-row > :last-child { grid-column: auto; color: var(--muted); }
  .table-row.table-head { display: none; }
  .faq-question { padding-right: 48px; font-size: 19px; }
  .faq-answer { padding-right: 0; }
  .entity-facts div { grid-template-columns: 1fr; gap: 4px; }
  .footer-grid { gap: 42px; }
  .footer-grid nav { display: grid; grid-template-columns: 1fr 1fr; }
  .footer-bottom { flex-direction: column; gap: 6px; }
  .store-grid { grid-template-columns: 1fr; }
  .dialog-head h2 { font-size: 32px; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *, *::before, *::after { transition-duration: .01ms !important; animation-duration: .01ms !important; }
}