:root {
  color-scheme: light;
  --blue: #0273fe;
  --blue-dark: #0057cc;
  --blue-soft: #e8f1ff;
  --navy: #0c1e3d;
  --text: #111827;
  --muted: #4b5563;
  --line: #e5e7eb;
  --soft: #f7f9fc;
  --white: #ffffff;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--text);
  background: var(--soft);
  font-family: -apple-system, BlinkMacSystemFont, "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", "Segoe UI", sans-serif;
  line-height: 1.7;
  -webkit-font-smoothing: antialiased;
}

a {
  color: var(--blue);
  text-decoration: none;
}

img {
  display: block;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  gap: 28px;
  min-height: 68px;
  padding: 0 48px;
  background: rgba(255, 255, 255, .96);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(16px);
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  color: var(--blue);
  font-size: 22px;
  font-weight: 800;
}

.brand img {
  height: 34px;
  width: auto;
}

.header-actions {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 22px;
  flex: 1;
  min-width: 0;
}

.nav-link {
  color: var(--muted);
  font-size: 14px;
  font-weight: 600;
  white-space: nowrap;
}

.nav-link:hover,
.nav-link[aria-current="page"] {
  color: var(--blue);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 40px;
  padding: 0 18px;
  border-radius: 8px;
  font-size: 14px;
  font-weight: 700;
  white-space: nowrap;
}

.button.primary {
  color: var(--white);
  background: var(--blue);
}

.button.primary:hover {
  background: var(--blue-dark);
}

.button.secondary {
  color: var(--navy);
  background: var(--white);
  border: 1px solid var(--line);
}

.content-hero {
  padding: 56px 48px 34px;
  background: linear-gradient(135deg, #ffffff 0%, #eef5ff 100%);
  border-bottom: 1px solid var(--line);
}

.content-hero-inner {
  width: min(1040px, 100%);
  margin: 0 auto;
}

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-bottom: 22px;
  color: var(--muted);
  font-size: 13px;
}

.breadcrumb span:last-child {
  color: var(--text);
  font-weight: 600;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--blue);
  font-size: 12px;
  font-weight: 800;
  letter-spacing: 2px;
  text-transform: uppercase;
}

h1 {
  max-width: 820px;
  margin: 0;
  color: var(--text);
  font-size: clamp(32px, 5vw, 48px);
  line-height: 1.16;
}

.content-intro {
  max-width: 760px;
  margin: 16px 0 0;
  color: var(--muted);
  font-size: 17px;
}

.summary-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 28px;
}

.summary-item {
  padding: 18px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.summary-item strong {
  display: block;
  margin-bottom: 6px;
  color: var(--text);
  font-size: 15px;
}

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

.content-page {
  padding: 42px 48px 64px;
}

.content-layout {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 28px;
  width: min(1040px, 100%);
  margin: 0 auto;
  align-items: start;
}

.content-toc {
  position: sticky;
  top: 88px;
  display: flex;
  flex-direction: column;
  gap: 10px;
  padding: 18px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.content-toc strong {
  color: var(--text);
  font-size: 13px;
}

.content-toc a {
  color: var(--muted);
  font-size: 13px;
  line-height: 1.45;
}

.content-toc a:hover {
  color: var(--blue);
}

.article-body {
  padding: 34px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.article-section {
  scroll-margin-top: 92px;
}

.article-section + .article-section {
  margin-top: 34px;
  padding-top: 30px;
  border-top: 1px solid var(--line);
}

h2 {
  margin: 0;
  color: var(--text);
  font-size: 24px;
  line-height: 1.35;
}

h3 {
  margin: 18px 0 0;
  color: var(--text);
  font-size: 18px;
}

p,
li {
  color: var(--muted);
}

p {
  margin: 12px 0 0;
}

ul {
  margin: 12px 0 0;
  padding-left: 22px;
}

.card-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.info-card,
.faq-item {
  padding: 20px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.info-card h3,
.faq-item h3 {
  margin-top: 0;
}

.related-links {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 12px;
  margin-top: 16px;
}

.related-links a {
  padding: 14px 16px;
  color: var(--navy);
  background: var(--blue-soft);
  border-radius: 8px;
  font-weight: 650;
}

.download-recommendation {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 24px;
  align-items: center;
  padding: 24px;
  margin-top: 18px;
  background: linear-gradient(135deg, #f8fbff 0%, #eaf3ff 100%);
  border: 1px solid #cfe2ff;
  border-radius: 8px;
}

.recommendation-badge {
  display: inline-flex;
  align-items: center;
  min-height: 28px;
  padding: 0 10px;
  color: var(--blue);
  background: var(--white);
  border: 1px solid #cfe2ff;
  border-radius: 999px;
  font-size: 12px;
  font-weight: 800;
}

.download-recommendation h2 {
  margin-top: 12px;
}

.download-actions {
  display: flex;
  flex-direction: column;
  gap: 10px;
  align-items: stretch;
  min-width: 220px;
}

.download-meta {
  color: var(--muted);
  font-size: 13px;
}

.platform-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.platform-card {
  display: flex;
  flex-direction: column;
  min-height: 236px;
  padding: 20px;
  background: var(--white);
  border: 1px solid var(--line);
  border-radius: 8px;
}

.platform-card.is-active {
  border-color: var(--blue);
  box-shadow: 0 14px 34px rgba(2, 115, 254, .12);
}

.platform-chip {
  display: inline-flex;
  align-items: center;
  align-self: flex-start;
  min-height: 26px;
  padding: 0 10px;
  color: var(--navy);
  background: var(--blue-soft);
  border-radius: 999px;
  font-size: 12px;
  font-weight: 800;
}

.platform-card h3 {
  margin-top: 14px;
}

.platform-card p {
  flex: 1;
}

.download-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 38px;
  margin-top: 16px;
  padding: 0 14px;
  color: var(--blue);
  background: var(--blue-soft);
  border-radius: 8px;
  font-weight: 800;
}

.official-note {
  margin-top: 18px;
  padding: 16px 18px;
  color: var(--muted);
  background: var(--soft);
  border: 1px solid var(--line);
  border-radius: 8px;
  font-size: 14px;
}

.cta-band {
  padding: 48px;
  color: var(--white);
  background: linear-gradient(135deg, #0c1e3d 0%, #1a3a8a 60%, #1d4ed8 100%);
}

.cta-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
  width: min(1040px, 100%);
  margin: 0 auto;
}

.cta-inner h2 {
  color: var(--white);
}

.cta-inner p {
  max-width: 620px;
  color: rgba(255, 255, 255, .78);
}

.site-footer {
  padding: 42px 48px 30px;
  background: #0c1425;
}

.footer-inner {
  display: grid;
  grid-template-columns: 1.3fr 2fr;
  gap: 36px;
  width: min(1040px, 100%);
  margin: 0 auto;
}

.footer-brand {
  color: var(--white);
  font-size: 18px;
  font-weight: 800;
}

.footer-note {
  max-width: 320px;
  margin-top: 10px;
  color: rgba(255, 255, 255, .48);
  font-size: 13px;
}

.footer-links {
  display: flex;
  flex-wrap: wrap;
  justify-content: flex-end;
  gap: 12px 18px;
}

.footer-links a {
  color: rgba(255, 255, 255, .68);
  font-size: 14px;
}

.footer-links a:hover {
  color: var(--white);
}

.footer-bottom {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  width: min(1040px, 100%);
  margin: 28px auto 0;
  padding-top: 22px;
  border-top: 1px solid rgba(255, 255, 255, .1);
  color: rgba(255, 255, 255, .36);
  font-size: 13px;
}

.footer-bottom a {
  color: rgba(255, 255, 255, .42);
}

.not-found-page {
  min-height: 52vh;
}

@media (max-width: 900px) {
  .site-header {
    padding: 0 20px;
    gap: 14px;
  }

  .header-actions {
    gap: 14px;
  }

  .header-actions .nav-link:nth-of-type(n + 4),
  .header-actions .button.secondary {
    display: none;
  }

  .content-layout {
    grid-template-columns: 1fr;
  }

  .content-toc {
    position: static;
  }

  .summary-grid,
  .card-grid,
  .platform-grid,
  .related-links {
    grid-template-columns: 1fr;
  }

  .download-recommendation {
    grid-template-columns: 1fr;
  }

  .download-actions {
    align-items: flex-start;
    min-width: 0;
  }

  .cta-inner,
  .footer-bottom {
    align-items: flex-start;
    flex-direction: column;
  }

  .footer-inner {
    grid-template-columns: 1fr;
  }

  .footer-links {
    justify-content: flex-start;
  }
}

@media (max-width: 640px) {
  .site-header {
    min-height: 60px;
    padding: 0 14px;
  }

  .brand {
    font-size: 19px;
  }

  .brand img {
    height: 28px;
  }

  .header-actions {
    gap: 10px;
  }

  .header-actions .nav-link:nth-of-type(n + 3) {
    display: none;
  }

  .button {
    min-height: 36px;
    padding: 0 12px;
    font-size: 13px;
  }

  .content-hero,
  .content-page,
  .cta-band,
  .site-footer {
    padding-left: 16px;
    padding-right: 16px;
  }

  .content-hero {
    padding-top: 36px;
  }

  .article-body {
    padding: 22px;
  }
}