:root {
  --blue: #229ed9;
  --blue-dark: #1477aa;
  --blue-soft: #e8f6fc;
  --ink: #17222b;
  --muted: #536270;
  --line: #dce7ef;
  --soft: #f3f8fb;
  --panel: #ffffff;
  --green: #138a62;
  --amber: #93640d;
  --dark: #102c3d;
  --radius: 8px;
  --shadow: 0 18px 50px rgba(23, 34, 43, 0.08);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(180deg, #edf7fc 0%, #ffffff 34%),
    #ffffff;
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", Arial, sans-serif;
  line-height: 1.72;
}

a {
  color: inherit;
}

img {
  max-width: 100%;
  display: block;
}

.wrap {
  width: min(1120px, calc(100% - 32px));
  margin: 0 auto;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 20;
  background: rgba(255, 255, 255, 0.92);
  border-bottom: 1px solid rgba(220, 231, 239, 0.86);
  backdrop-filter: blur(16px);
}

.top-strip {
  border-bottom: 1px solid rgba(220, 231, 239, 0.72);
  background: #f8fbfd;
  color: var(--muted);
  font-size: 13px;
}

.top-strip-inner {
  min-height: 34px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
}

.top-strip strong {
  color: var(--blue-dark);
}

.top-links {
  display: flex;
  gap: 12px;
  white-space: nowrap;
}

.top-links a {
  color: var(--blue-dark);
  text-decoration: none;
  font-weight: 700;
}

.nav {
  min-height: 78px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 22px;
}

.brand {
  min-width: max-content;
  display: inline-flex;
  align-items: center;
  gap: 12px;
  color: var(--ink);
  text-decoration: none;
}

.brand img {
  width: 44px;
  height: 44px;
  border-radius: 8px;
}

.brand-copy {
  display: grid;
  gap: 1px;
}

.brand-copy strong,
.brand > span {
  font-size: 17px;
  font-weight: 900;
  line-height: 1.1;
  white-space: nowrap;
}

.brand-copy span {
  color: var(--muted);
  font-size: 12px;
  line-height: 1.2;
  white-space: nowrap;
}

.nav-links {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 6px;
  color: var(--muted);
  font-size: 14px;
}

.nav-links a {
  min-height: 38px;
  display: inline-flex;
  align-items: center;
  padding: 8px 11px;
  border-radius: var(--radius);
  text-decoration: none;
  font-weight: 750;
  white-space: nowrap;
}

.nav-links a:hover,
.nav-links a[aria-current="page"] {
  background: var(--blue-soft);
  color: var(--blue-dark);
}

.nav-cta {
  min-height: 40px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 9px 14px;
  border-radius: var(--radius);
  background: var(--blue);
  color: #ffffff;
  font-size: 14px;
  font-weight: 850;
  text-decoration: none;
  white-space: nowrap;
}

.hero {
  padding: 68px 0 46px;
}

.hero-grid {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(320px, 0.85fr);
  gap: 44px;
  align-items: center;
}

.eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 16px;
  color: var(--blue-dark);
  font-size: 14px;
  font-weight: 850;
}

.eyebrow::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--blue);
  box-shadow: 0 0 0 5px rgba(34, 158, 217, 0.14);
}

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

h1 {
  max-width: 760px;
  margin-bottom: 18px;
  font-size: clamp(36px, 5vw, 60px);
  line-height: 1.08;
  letter-spacing: 0;
}

.lead {
  max-width: 720px;
  margin-bottom: 26px;
  color: var(--muted);
  font-size: 18px;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-bottom: 22px;
}

.btn {
  min-height: 48px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 12px 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
  color: var(--ink);
  font-weight: 850;
  text-decoration: none;
  box-shadow: 0 8px 20px rgba(23, 34, 43, 0.06);
}

.btn.primary {
  border-color: var(--blue);
  background: var(--blue);
  color: #ffffff;
}

.btn.ghost {
  background: transparent;
  box-shadow: none;
}

.btn:hover,
.nav-cta:hover {
  transform: translateY(-1px);
  box-shadow: 0 12px 24px rgba(23, 34, 43, 0.1);
}

.trust-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  padding: 0;
  margin: 0;
  list-style: none;
  color: var(--muted);
  font-size: 14px;
}

.trust-list li {
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.74);
}

.download-panel {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.9);
  box-shadow: var(--shadow);
  overflow: hidden;
}

.panel-head {
  display: flex;
  align-items: center;
  gap: 14px;
  padding: 22px;
  border-bottom: 1px solid var(--line);
  background: #ffffff;
}

.panel-head img {
  width: 56px;
  height: 56px;
  border-radius: var(--radius);
}

.panel-head strong {
  display: block;
  font-size: 20px;
}

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

.quick-list {
  display: grid;
  gap: 0;
}

.quick-item {
  display: grid;
  grid-template-columns: 1fr auto;
  gap: 12px;
  align-items: center;
  padding: 18px 22px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
}

.quick-item:last-child {
  border-bottom: 0;
}

.quick-item:hover {
  background: var(--soft);
}

.quick-item > span:first-child {
  color: var(--ink);
  font-size: 16px;
}

.quick-item strong {
  display: block;
}

.quick-item > span:first-child > span {
  color: var(--muted);
  font-size: 14px;
}

.arrow {
  color: var(--blue-dark);
  font-weight: 900;
}

section {
  padding: 38px 0;
}

.section-title {
  max-width: 780px;
  margin-bottom: 22px;
}

.section-title h2 {
  margin-bottom: 8px;
  font-size: clamp(26px, 3vw, 38px);
  line-height: 1.18;
  letter-spacing: 0;
}

.section-title p {
  color: var(--muted);
}

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

.card,
.topic-card,
.article-card,
.compare-box,
.toc,
.note-box {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--panel);
  box-shadow: 0 10px 24px rgba(23, 34, 43, 0.04);
}

.card,
.topic-card,
.article-card {
  overflow: hidden;
}

.card-body,
.topic-card,
.article-card {
  padding: 20px;
}

.card h3,
.topic-card h3,
.article-card h3 {
  margin-bottom: 8px;
  font-size: 20px;
}

.card p,
.topic-card p,
.article-card p {
  color: var(--muted);
  font-size: 15px;
}

.card .btn,
.article-card .btn {
  width: 100%;
  min-height: 44px;
  box-shadow: none;
}

.topic-card {
  display: grid;
  gap: 10px;
  text-decoration: none;
}

.topic-card:hover,
.article-card:hover {
  border-color: rgba(34, 158, 217, 0.44);
  transform: translateY(-1px);
}

.topic-meta {
  color: var(--blue-dark);
  font-size: 13px;
  font-weight: 850;
}

.badge {
  display: inline-flex;
  align-items: center;
  padding: 4px 9px;
  margin-bottom: 12px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  font-size: 13px;
  font-weight: 850;
}

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

.compare-box {
  padding: 22px;
}

.compare-box h3 {
  margin-bottom: 10px;
}

.compare-box ul,
.steps,
.check-list,
.prose ul,
.prose ol {
  margin: 0;
  padding-left: 20px;
  color: var(--muted);
}

.compare-box li,
.steps li,
.check-list li,
.prose li {
  margin: 8px 0;
}

.notice {
  padding: 18px 20px;
  border: 1px solid #f0d697;
  border-left: 4px solid #d69723;
  border-radius: var(--radius);
  background: #fff9eb;
  color: var(--amber);
}

.guide-grid {
  display: grid;
  grid-template-columns: minmax(0, 0.95fr) minmax(0, 1.05fr);
  gap: 16px;
  align-items: start;
}

.info-band {
  padding: 28px;
  border-radius: var(--radius);
  background: var(--dark);
  color: #ffffff;
}

.info-band p {
  color: rgba(255, 255, 255, 0.82);
}

.faq {
  display: grid;
  gap: 12px;
}

details {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
}

summary {
  cursor: pointer;
  padding: 18px 20px;
  font-weight: 850;
}

details p {
  margin: 0;
  padding: 0 20px 18px;
  color: var(--muted);
}

.page-hero {
  padding: 48px 0 26px;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 16px;
  color: var(--muted);
  font-size: 14px;
}

.breadcrumb a {
  color: var(--blue-dark);
  text-decoration: none;
  font-weight: 750;
}

.page-kicker {
  color: var(--blue-dark);
  font-size: 14px;
  font-weight: 850;
}

.page-hero h1 {
  font-size: clamp(32px, 4vw, 52px);
}

.official-panel {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 18px;
  align-items: center;
  padding: 22px;
  border: 1px solid rgba(34, 158, 217, 0.28);
  border-radius: var(--radius);
  background:
    linear-gradient(135deg, rgba(34, 158, 217, 0.1), rgba(255, 255, 255, 0.92)),
    #ffffff;
  box-shadow: var(--shadow);
}

.official-panel strong {
  display: block;
  margin-bottom: 6px;
  font-size: 22px;
}

.official-panel p {
  margin-bottom: 0;
  color: var(--muted);
}

.official-mark {
  display: inline-flex;
  align-items: center;
  min-height: 32px;
  padding: 5px 10px;
  border-radius: 999px;
  background: var(--blue-soft);
  color: var(--blue-dark);
  font-size: 13px;
  font-weight: 850;
  white-space: nowrap;
}

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

.summary-item {
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
}

.summary-item span {
  display: block;
  margin-bottom: 8px;
  color: var(--blue-dark);
  font-size: 13px;
  font-weight: 850;
}

.summary-item strong {
  display: block;
  margin-bottom: 8px;
  font-size: 20px;
}

.summary-item p {
  margin-bottom: 0;
  color: var(--muted);
  font-size: 15px;
}

.content-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) 300px;
  gap: 24px;
  align-items: start;
}

.prose {
  padding: 28px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
}

.prose h2 {
  margin: 30px 0 10px;
  font-size: 28px;
  line-height: 1.22;
}

.prose h2:first-child {
  margin-top: 0;
}

.prose h3 {
  margin: 22px 0 8px;
  font-size: 21px;
}

.prose p {
  color: var(--muted);
}

.prose a {
  color: var(--blue-dark);
  font-weight: 750;
}

.toc {
  position: sticky;
  top: 116px;
  padding: 18px;
}

.toc strong {
  display: block;
  margin-bottom: 10px;
}

.toc a {
  display: block;
  padding: 7px 0;
  color: var(--muted);
  text-decoration: none;
  font-size: 14px;
}

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

.download-table {
  width: 100%;
  border-collapse: collapse;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
}

.download-table th,
.download-table td {
  padding: 13px 14px;
  border-bottom: 1px solid var(--line);
  text-align: left;
  vertical-align: top;
}

.download-table th {
  background: var(--soft);
  color: var(--ink);
}

.download-table tr:last-child td {
  border-bottom: 0;
}

.download-table a {
  color: var(--blue-dark);
  font-weight: 850;
}

.note-box {
  padding: 20px;
}

.note-box strong {
  color: var(--ink);
}

/* Quick spec strip under page hero */
.spec-strip {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
  margin-top: 26px;
}

.spec {
  padding: 14px 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: rgba(255, 255, 255, 0.74);
}

.spec b {
  display: block;
  margin-bottom: 2px;
  color: var(--blue-dark);
  font-size: 12px;
  font-weight: 850;
  letter-spacing: 0.02em;
  text-transform: uppercase;
}

.spec span {
  color: var(--ink);
  font-size: 15px;
  font-weight: 800;
}

/* Featured-answer box (snippet target) */
.answer-box {
  padding: 20px 22px;
  border: 1px solid rgba(34, 158, 217, 0.28);
  border-left: 4px solid var(--blue);
  border-radius: var(--radius);
  background:
    linear-gradient(135deg, rgba(34, 158, 217, 0.08), rgba(255, 255, 255, 0.95)),
    #ffffff;
}

.answer-box strong {
  display: block;
  margin-bottom: 6px;
  color: var(--ink);
  font-size: 17px;
}

.answer-box p {
  margin: 0;
  color: var(--muted);
}

/* Numbered step list */
.step-list {
  counter-reset: step;
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.step-list li {
  position: relative;
  padding: 14px 16px 14px 54px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #ffffff;
  color: var(--muted);
}

.step-list li::before {
  counter-increment: step;
  content: counter(step);
  position: absolute;
  left: 14px;
  top: 13px;
  width: 28px;
  height: 28px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--blue);
  color: #ffffff;
  font-size: 14px;
  font-weight: 850;
}

.step-list li b,
.step-list li strong {
  color: var(--ink);
}

@media (max-width: 780px) {
  .spec-strip {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}

.article-meta {
  margin-bottom: 12px;
  color: var(--muted);
  font-size: 14px;
}

.site-footer {
  margin-top: 34px;
  padding: 0;
  border-top: 1px solid var(--line);
  background: #f8fbfd;
  color: var(--muted);
  font-size: 14px;
}

.footer-main {
  display: grid;
  grid-template-columns: minmax(260px, 1.2fr) repeat(3, minmax(140px, 0.65fr));
  gap: 24px;
  padding: 38px 0;
}

.footer-brand {
  display: flex;
  gap: 12px;
  align-items: flex-start;
}

.footer-brand img {
  width: 46px;
  height: 46px;
  border-radius: var(--radius);
}

.footer-brand strong,
.footer-col strong {
  display: block;
  margin-bottom: 8px;
  color: var(--ink);
  font-size: 16px;
}

.footer-brand p {
  max-width: 430px;
  margin-bottom: 0;
}

.footer-col {
  display: grid;
  align-content: start;
  gap: 8px;
}

.footer-col a {
  color: var(--muted);
  text-decoration: none;
}

.footer-col a:hover {
  color: var(--blue-dark);
}

.footer-bottom {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  padding: 18px 0;
  border-top: 1px solid var(--line);
}

.footer-bottom a {
  color: var(--blue-dark);
  text-decoration: none;
  font-weight: 750;
}

@media (max-width: 980px) {
  .nav {
    align-items: flex-start;
    flex-direction: column;
    padding: 14px 0;
  }

  .nav-links {
    width: 100%;
    justify-content: flex-start;
    overflow-x: auto;
    padding-bottom: 4px;
  }

  .nav-cta {
    width: 100%;
  }

  .hero {
    padding-top: 42px;
  }

  .hero-grid,
  .guide-grid,
  .compare,
  .official-panel,
  .summary-grid,
  .content-layout,
  .footer-main,
  .footer-bottom {
    grid-template-columns: 1fr;
  }

  .cards,
  .topic-grid,
  .article-grid {
    grid-template-columns: 1fr;
  }

  .toc {
    position: static;
  }
}

@media (max-width: 620px) {
  .wrap {
    width: min(100% - 24px, 1120px);
  }

  .top-strip-inner {
    align-items: flex-start;
    flex-direction: column;
    padding: 8px 0;
  }

  .brand-copy span {
    display: none;
  }

  h1 {
    font-size: 34px;
  }

  .lead {
    font-size: 16px;
  }

  .actions .btn,
  .quick-item {
    width: 100%;
  }

  .quick-item {
    grid-template-columns: 1fr;
  }

  .prose {
    padding: 20px;
  }

  .download-table,
  .download-table tbody,
  .download-table tr,
  .download-table th,
  .download-table td {
    display: block;
    width: 100%;
  }

  .download-table thead {
    display: none;
  }

  .download-table td {
    border-bottom: 0;
  }

  .download-table tr {
    border-bottom: 1px solid var(--line);
  }
}