:root {
  --bg: #f6f7f9;
  --surface: #ffffff;
  --surface-soft: #f9fbfd;
  --text: #24303c;
  --text-secondary: #66717d;
  --heading: #2f4f6f;
  --primary: #4a7db8;
  --primary-soft: #eaf2ff;
  --border: #dbe2ea;
  --border-strong: #c8d2df;
  --highlight: #fff7db;
  --highlight-border: #f0d88b;
  --shadow: 0 14px 36px rgba(46, 79, 111, 0.08);
  --radius-lg: 20px;
  --radius-md: 14px;
  --radius-sm: 10px;
  --container: 1180px;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
}

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

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

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

.hero {
  padding: 56px 0 28px;
}

.hero__inner {
  display: grid;
  grid-template-columns: 1.45fr 0.95fr;
  gap: 28px;
  align-items: stretch;
}

.hero__content,
.hero__panel .panel-card {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 28px;
  box-shadow: var(--shadow);
}

.hero__content {
  padding: 40px;
}

.eyebrow,
.section-heading__eyebrow {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  margin: 0 0 14px;
  color: var(--primary);
  font-size: 13px;
  font-weight: 700;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.eyebrow::before,
.section-heading__eyebrow::before {
  content: "";
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background: var(--primary);
  opacity: 0.3;
}

.hero h1 {
  margin: 0 0 14px;
  color: var(--heading);
  font-size: clamp(32px, 5vw, 48px);
  line-height: 1.18;
}

.hero__subtitle {
  margin: 0 0 20px;
  max-width: 780px;
  color: var(--text-secondary);
  font-size: 17px;
}

.hero__meta,
.tags {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.meta-chip,
.tags span,
.tag {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 32px;
  padding: 6px 12px;
  border: 1px solid var(--border);
  border-radius: 999px;
  background: #fbfcfe;
  color: var(--text-secondary);
  font-size: 13px;
}

.hero__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 28px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 46px;
  padding: 0 18px;
  border-radius: 999px;
  border: 1px solid transparent;
  font-weight: 700;
  transition: all 0.2s ease;
}

.btn:hover,
.text-link:hover,
.path-card__actions a:hover,
.recommend-card a:hover,
.back-top:hover {
  transform: translateY(-1px);
}

.btn--primary {
  background: var(--primary);
  color: #fff;
  box-shadow: 0 10px 20px rgba(74, 125, 184, 0.22);
}

.btn--secondary {
  background: var(--primary-soft);
  border-color: #cddfff;
  color: var(--primary);
}

.btn--ghost {
  background: #fff;
  border-color: var(--border);
  color: var(--heading);
}

.panel-card {
  padding: 28px;
  height: 100%;
}

.panel-card__title {
  margin-bottom: 18px;
  color: var(--heading);
  font-size: 18px;
  font-weight: 800;
}

.flow-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  gap: 12px;
}

.flow-list li {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  padding: 14px 16px;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  background: var(--surface-soft);
}

.flow-list strong {
  color: var(--heading);
  font-size: 15px;
}

.flow-list span {
  color: var(--text-secondary);
  font-size: 14px;
}

.panel-card__note {
  margin: 18px 0 0;
  padding: 14px 16px;
  border-left: 4px solid var(--highlight-border);
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
  background: var(--highlight);
  color: #6a5731;
  font-size: 14px;
}

.section {
  padding: 38px 0;
}

.section--alt {
  background: linear-gradient(180deg, rgba(255,255,255,0.55) 0%, rgba(245,247,250,0.85) 100%);
}

.section-heading {
  margin-bottom: 24px;
}

.section-heading h2 {
  margin: 0 0 8px;
  color: var(--heading);
  font-size: clamp(26px, 4vw, 34px);
}

.section-heading p {
  margin: 0;
  max-width: 760px;
  color: var(--text-secondary);
}

.path-grid,
.chapter-grid,
.recommend-grid,
.term-grid {
  display: grid;
  gap: 18px;
}

.path-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.chapter-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.recommend-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
}

.term-grid {
  grid-template-columns: repeat(3, minmax(0, 1fr));
}

.path-card,
.chapter-card,
.recommend-card,
.term-card {
  position: relative;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

.path-card {
  padding: 24px 22px 22px;
}

.path-card__number {
  width: 52px;
  height: 52px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 16px;
  background: var(--primary-soft);
  border: 1px solid #d4e3ff;
  color: var(--primary);
  font-weight: 800;
  font-size: 18px;
}

.path-card h3,
.chapter-card h3,
.recommend-card h3,
.term-card h3,
.site-footer h2 {
  margin: 16px 0 10px;
  color: var(--heading);
}

.path-card p,
.chapter-card p,
.recommend-card ol,
.term-card p,
.site-footer p {
  margin: 0;
  color: var(--text-secondary);
}

.path-card__list {
  margin: 14px 0 18px;
  padding-left: 18px;
  color: var(--text-secondary);
}

.path-card__actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 16px;
}

.path-card__actions a,
.text-link,
.recommend-card a,
.back-top {
  color: var(--primary);
  font-weight: 700;
}

.chapter-card {
  padding: 22px;
}

.chapter-card__header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin-bottom: 12px;
}

.chapter-card__index {
  display: inline-flex;
  padding: 6px 10px;
  border-radius: 10px;
  background: #f2f5f9;
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 700;
}

.featured {
  border-color: #cfe0fb;
  background: linear-gradient(180deg, #ffffff 0%, #f7fbff 100%);
}

.featured-soft {
  border-color: #d7e6ff;
  background: linear-gradient(180deg, #ffffff 0%, #fafcff 100%);
}

.recommend-card {
  padding: 22px;
}

.recommend-card ol {
  margin-top: 12px;
  padding-left: 20px;
}

.recommend-card li + li {
  margin-top: 8px;
}

.term-card {
  padding: 20px 20px 18px;
  background: linear-gradient(180deg, #fffdf4 0%, #fff9e8 100%);
  border-color: #efdfab;
}

.term-card::before {
  content: "术语";
  display: inline-flex;
  margin-bottom: 10px;
  padding: 4px 10px;
  border-radius: 999px;
  background: rgba(240, 216, 139, 0.28);
  color: #8a6a1f;
  font-size: 12px;
  font-weight: 700;
}

.chapter-nav-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}

.nav-card {
  display: block;
  padding: 22px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

.nav-card strong {
  display: block;
  margin-bottom: 8px;
  color: var(--heading);
  font-size: 18px;
}

.nav-card p {
  margin: 0;
  color: var(--text-secondary);
}

.nav-card__index,
.doc-section__index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  margin-bottom: 12px;
  padding: 6px 10px;
  border-radius: 999px;
  background: var(--primary-soft);
  border: 1px solid #d4e3ff;
  color: var(--primary);
  font-size: 13px;
  font-weight: 700;
}

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

.chapter-sidebar {
  position: sticky;
  top: 20px;
}

.sidebar-card {
  padding: 20px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow);
}

.sidebar-card + .sidebar-card {
  margin-top: 16px;
}

.sidebar-card--highlight {
  background: linear-gradient(180deg, #fffdf4 0%, #fff9e8 100%);
  border-color: #efdfab;
}

.sidebar-card__title {
  margin: 0 0 12px;
  color: var(--heading);
  font-weight: 800;
}

.sidebar-nav {
  display: grid;
  gap: 10px;
}

.sidebar-nav a {
  display: block;
  padding: 10px 12px;
  border-radius: var(--radius-sm);
  background: var(--surface-soft);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}

.chapter-content {
  display: grid;
  gap: 24px;
}

.doc-section {
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.doc-section__header h2 {
  margin: 0 0 8px;
  color: var(--heading);
  font-size: clamp(28px, 4vw, 36px);
}

.doc-section__header p {
  margin: 0;
  color: var(--text-secondary);
}

.content-card {
  margin-top: 18px;
  padding: 20px;
  background: var(--surface-soft);
  border: 1px solid var(--border);
  border-radius: 18px;
}

.content-card h3,
.content-card h4 {
  margin-top: 0;
  margin-bottom: 10px;
  color: var(--heading);
}

.knowledge-box {
  margin-top: 18px;
  padding: 18px 20px;
  border-left: 5px solid var(--highlight-border);
  border-radius: 0 16px 16px 0;
  background: var(--highlight);
}

.knowledge-box--soft {
  background: #f8fbff;
  border-left-color: #b8d1f5;
}

.knowledge-box strong {
  display: block;
  margin-bottom: 6px;
  color: #725720;
}

.step-strip {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 12px;
  margin-bottom: 14px;
}

.step-strip__item {
  display: grid;
  gap: 6px;
  padding: 14px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 16px;
  text-align: center;
}

.step-strip__item span {
  width: 32px;
  height: 32px;
  margin: 0 auto;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  border-radius: 50%;
  background: var(--primary-soft);
  color: var(--primary);
  font-weight: 800;
}

.step-strip__item strong {
  color: var(--heading);
}

.step-strip__item em {
  color: var(--text-secondary);
  font-style: normal;
  font-size: 13px;
}

.inline-note-list {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-bottom: 12px;
}

.inline-note-list span {
  padding: 8px 12px;
  border-radius: 999px;
  background: #fff;
  border: 1px solid var(--border);
  color: var(--text-secondary);
}

.feature-list {
  margin: 0;
  padding-left: 20px;
  color: var(--text-secondary);
}

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

.table-wrap {
  overflow-x: auto;
}

table {
  width: 100%;
  border-collapse: collapse;
  background: #fff;
  border-radius: 12px;
  overflow: hidden;
}

th,
 td {
  padding: 12px 14px;
  border: 1px solid var(--border);
  text-align: left;
}

th {
  background: #f2f5f9;
  color: var(--heading);
}

.small-note {
  margin-top: 12px;
  font-size: 14px;
}

.mini-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 14px;
}

.mini-card {
  padding: 16px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: 14px;
}

pre {
  margin: 0;
  padding: 16px;
  overflow-x: auto;
  background: #1f2630;
  color: #ecf2fb;
  border-radius: 14px;
  font-size: 13px;
  line-height: 1.65;
}

code {
  font-family: Consolas, Monaco, "Courier New", monospace;
}

.next-links__card {
  padding: 28px;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 24px;
  box-shadow: var(--shadow);
}

.footer__inner {
  display: grid;
  gap: 16px;
  padding: 26px;
  border: 1px solid var(--border);
  border-radius: 24px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.footer__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 18px;
  color: var(--text-secondary);
  font-size: 14px;
}

.back-top {
  justify-self: start;
}

@media (max-width: 1080px) {
  .hero__inner,
  .path-grid,
  .chapter-grid,
  .term-grid,
  .recommend-grid,
  .chapter-nav-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

  .chapter-sidebar {
    position: static;
  }

  .step-strip {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .hero__content {
    grid-column: 1 / -1;
  }

  .hero__panel {
    grid-column: 1 / -1;
  }
}

@media (max-width: 720px) {
  .container {
    width: min(var(--container), calc(100% - 24px));
  }

  .hero {
    padding-top: 28px;
  }

  .hero__content,
  .panel-card,
  .path-card,
  .chapter-card,
  .recommend-card,
  .term-card,
  .footer__inner,
  .doc-section,
  .next-links__card,
  .sidebar-card,
  .nav-card,
  .content-card {
    padding-left: 18px;
    padding-right: 18px;
  }

  .hero__inner,
  .path-grid,
  .chapter-grid,
  .term-grid,
  .recommend-grid,
  .chapter-nav-grid,
  .mini-grid,
  .step-strip {
    grid-template-columns: 1fr;
  }

  .hero__actions,
  .hero__meta,
  .path-card__actions,
  .footer__meta,
  .inline-note-list {
    flex-direction: column;
    align-items: flex-start;
  }

  .btn {
    width: 100%;
  }

  .chapter-card__header,
  .flow-list li {
    flex-direction: column;
    align-items: flex-start;
  }
}

/* ── SVG 图表容器 ── */
.svg-figure {
  margin: 32px 0;
  padding: 24px 16px 16px;
  background: #fff;
  border: 1px solid var(--border);
  border-radius: var(--radius-md);
  box-shadow: 0 4px 16px rgba(46,79,111,0.06);
  text-align: center;
}

.svg-figure img {
  height: auto;
}

.svg-caption {
  margin: 10px 0 0;
  font-size: 12px;
  color: var(--text-secondary);
  letter-spacing: 0.01em;
}

/* ── 首页署名 ── */
.hero__credit {
  margin: 20px 0 0;
  padding: 12px 16px;
  border-left: 3px solid var(--primary);
  background: var(--primary-soft);
  border-radius: 0 8px 8px 0;
  font-size: 14px;
  color: var(--text-secondary);
  letter-spacing: 0.03em;
}

.hero__credit strong {
  color: var(--primary);
  font-weight: 700;
  font-size: 15px;
}