:root {
  --bg: #f6f4ef;
  --surface: #ffffff;
  --surface-muted: #faf8f3;
  --surface-deep: #f0ece3;
  --ink: #1d2530;
  --muted: #5f6670;
  --line: rgba(29, 37, 48, 0.14);
  --line-strong: rgba(29, 37, 48, 0.22);
  --navy: #183049;
  --navy-soft: #35506c;
  --accent: #8a5b3d;
  --accent-soft: #d6b89d;
  --radius-xl: 22px;
  --radius-lg: 16px;
  --radius-md: 12px;
  --shadow-soft: 0 18px 40px rgba(24, 48, 73, 0.06);
  --content-width: min(1040px, calc(100vw - 40px));
  --heading-font: "Source Han Serif SC", "Noto Serif SC", "Songti SC", serif;
  --body-font: "Noto Sans SC", "HarmonyOS Sans SC", "PingFang SC", "Helvetica Neue", "Microsoft YaHei", sans-serif;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  min-height: 100vh;
  color: var(--ink);
  font-family: var(--body-font);
  background:
    radial-gradient(circle at top right, rgba(138, 91, 61, 0.08), transparent 18%),
    linear-gradient(180deg, #f3f1ec 0%, #f8f6f1 100%);
}

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

button,
input,
select,
textarea {
  font: inherit;
}

.detail-shell {
  width: var(--content-width);
  margin: 0 auto;
  padding: 28px 0 54px;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
  padding: 14px 0 16px;
  border-bottom: 1px solid var(--line);
  background: rgba(246, 244, 239, 0.94);
  backdrop-filter: blur(10px);
}

.brand {
  display: flex;
  flex-direction: column;
  gap: 2px;
  min-width: 0;
  color: var(--navy);
}

.brand-kicker {
  color: var(--accent);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

.brand strong {
  font-size: 1rem;
  font-weight: 700;
}

.site-nav {
  display: flex;
  align-items: center;
  gap: 18px;
}

.site-nav a {
  color: rgba(24, 48, 73, 0.82);
  font-size: 0.95rem;
}

.site-nav a:hover,
.site-nav a.is-active {
  color: var(--navy);
  text-decoration: underline;
  text-underline-offset: 5px;
}

.menu-toggle {
  display: none;
  border: 1px solid var(--line);
  border-radius: 999px;
  padding: 8px 14px;
  color: var(--navy);
  background: var(--surface);
  cursor: pointer;
}

main {
  display: grid;
  gap: 30px;
  margin-top: 28px;
}

.detail-hero {
  display: grid;
  grid-template-columns: minmax(0, 1.25fr) minmax(260px, 0.8fr);
  gap: 28px;
  align-items: start;
}

.hero-copy,
.hero-panel,
.demo-panel,
.section-card {
  min-width: 0;
}

.eyebrow {
  margin: 0;
  color: var(--accent);
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

.detail-hero h1,
.hero-panel h2,
.section-heading h2,
.section-card h3,
.doc-button span,
.mode-button strong,
.demo-surface h3 {
  font-family: var(--heading-font);
}

.detail-hero h1 {
  margin: 14px 0 0;
  color: var(--navy);
  font-size: clamp(2.8rem, 5vw, 4.2rem);
  line-height: 1.02;
}

.hero-lead {
  margin: 18px 0 0;
  max-width: 28ch;
  color: var(--ink);
  font-size: clamp(1.18rem, 2.1vw, 1.5rem);
  line-height: 1.52;
}

.hero-copy p:last-of-type,
.hero-panel p,
.section-heading p,
.section-card p,
.reader-meta,
.assistant-meta {
  color: var(--muted);
  line-height: 1.86;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 24px;
}

.action-link,
.subtle-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 999px;
  padding: 11px 18px;
  font-weight: 700;
}

.action-link {
  color: var(--surface);
  background: var(--navy);
}

.action-link:hover {
  background: var(--navy-soft);
}

.subtle-link {
  color: var(--navy);
  background: rgba(24, 48, 73, 0.08);
}

.hero-panel,
.section-card,
.demo-panel {
  padding: 20px 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background: var(--surface);
  box-shadow: var(--shadow-soft);
}

.hero-panel h2,
.section-card h3 {
  margin: 0;
  color: var(--navy);
  font-size: 1.3rem;
}

.plain-list {
  margin: 16px 0 0;
  padding-left: 18px;
  color: var(--muted);
  line-height: 1.85;
}

.plain-list li + li {
  margin-top: 8px;
}

.capability-grid,
.section-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
}

.section-heading h2 {
  margin: 10px 0 0;
  color: var(--navy);
  font-size: clamp(1.9rem, 3vw, 2.8rem);
  line-height: 1.14;
}

.section-heading p:last-child {
  margin: 12px 0 0;
}

.demo-layout {
  display: grid;
  grid-template-columns: minmax(220px, 0.34fr) minmax(0, 0.66fr);
  gap: 18px;
}

.doc-list,
.mode-list {
  display: grid;
  gap: 12px;
}

.doc-button,
.mode-button {
  width: 100%;
  display: grid;
  gap: 8px;
  padding: 16px 16px 15px;
  text-align: left;
  border: 1px solid var(--line);
  border-radius: var(--radius-lg);
  background: var(--surface-muted);
  cursor: pointer;
  transition:
    border-color 180ms ease,
    transform 180ms ease,
    background-color 180ms ease;
}

.doc-button:hover,
.mode-button:hover,
.doc-button.is-active,
.mode-button.is-active {
  border-color: var(--line-strong);
  background: var(--surface);
  transform: translateY(-1px);
}

.doc-button span,
.mode-button strong {
  color: var(--navy);
  font-size: 1.06rem;
}

.doc-button small,
.mode-button small {
  color: var(--muted);
  line-height: 1.7;
}

.demo-surface {
  min-height: 560px;
  display: grid;
  gap: 20px;
}

.reader-frame,
.assistant-frame {
  display: grid;
  gap: 18px;
  min-height: 100%;
  padding: 22px;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background: linear-gradient(180deg, var(--surface) 0%, var(--surface-muted) 100%);
}

.reader-header,
.assistant-header {
  display: grid;
  gap: 8px;
  padding-bottom: 16px;
  border-bottom: 1px solid rgba(29, 37, 48, 0.08);
}

.reader-header h3,
.assistant-header h3 {
  margin: 0;
  color: var(--navy);
  font-size: 1.42rem;
}

.reader-body {
  color: var(--ink);
  line-height: 1.9;
}

.reader-body h1,
.reader-body h2,
.reader-body h3,
.assistant-response h4 {
  color: var(--navy);
  font-family: var(--heading-font);
}

.reader-body h1 {
  margin: 0 0 16px;
  font-size: 1.8rem;
}

.reader-body h2 {
  margin: 28px 0 10px;
  font-size: 1.34rem;
}

.reader-body h3 {
  margin: 22px 0 8px;
  font-size: 1.12rem;
}

.reader-body p,
.assistant-response p {
  margin: 0 0 14px;
}

.reader-body ul,
.assistant-response ul {
  margin: 0 0 14px;
  padding-left: 20px;
}

.reader-outline,
.assistant-notes {
  padding: 16px 18px;
  border-radius: var(--radius-lg);
  background: var(--surface-deep);
}

.reader-outline h4,
.assistant-notes h4 {
  margin: 0 0 10px;
  color: var(--navy);
  font-size: 0.94rem;
}

.reader-outline ul,
.assistant-notes ul {
  margin: 0;
  padding-left: 18px;
  color: var(--muted);
  line-height: 1.8;
}

.assistant-response {
  color: var(--ink);
  line-height: 1.85;
}

.assistant-response section + section {
  margin-top: 18px;
  padding-top: 18px;
  border-top: 1px solid rgba(29, 37, 48, 0.08);
}

.assistant-response h4 {
  margin: 0 0 10px;
  font-size: 1.04rem;
}

.redirect-page {
  display: grid;
  place-items: center;
  min-height: calc(100vh - 40px);
}

.redirect-card {
  width: min(560px, calc(100vw - 40px));
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius-xl);
  background: var(--surface);
  box-shadow: var(--shadow-soft);
}

.redirect-card h1 {
  margin: 12px 0 0;
  color: var(--navy);
  font-family: var(--heading-font);
  font-size: clamp(2rem, 5vw, 2.8rem);
}

.redirect-card p {
  margin: 14px 0 0;
  color: var(--muted);
  line-height: 1.8;
}

.redirect-card .action-link,
.redirect-card .subtle-link {
  margin-top: 18px;
}

.page-footer {
  margin-top: 30px;
  padding-top: 18px;
  border-top: 1px solid var(--line);
}

.footer-note {
  margin: 0;
  color: var(--muted);
  font-size: 0.94rem;
}

[data-reveal] {
  opacity: 1;
  transform: none;
}

[data-reveal].is-visible {
  opacity: 1;
  transform: none;
}

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

  [data-reveal] {
    opacity: 1;
    transform: none;
  }
}

@media (max-width: 920px) {
  .detail-hero,
  .capability-grid,
  .section-grid,
  .demo-layout {
    grid-template-columns: 1fr;
  }

  .menu-toggle {
    display: inline-flex;
  }

  .site-nav {
    position: absolute;
    top: calc(100% + 10px);
    right: 0;
    flex-direction: column;
    align-items: stretch;
    min-width: 220px;
    padding: 12px;
    border: 1px solid var(--line);
    border-radius: var(--radius-md);
    background: var(--surface);
    opacity: 0;
    pointer-events: none;
    transform: translateY(-6px);
    transition:
      opacity 180ms ease,
      transform 180ms ease;
  }

  .site-nav.is-open {
    opacity: 1;
    pointer-events: auto;
    transform: translateY(0);
  }

  .demo-surface {
    min-height: unset;
  }
}

@media (max-width: 720px) {
  :root {
    --content-width: min(100vw - 24px, 1040px);
  }

  .detail-shell {
    padding-top: 18px;
  }

  .topbar {
    align-items: flex-start;
  }

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
  }

  .reader-frame,
  .assistant-frame,
  .redirect-card {
    padding: 18px;
  }
}