:root {
  --paper: #f3eee4;
  --paper-2: #ebe4d4;
  --ink: #1a1612;
  --ink-soft: #534c43;
  --rule: #c8bfb0;
  --rule-fine: #ddd3c4;
  --accent: #0e4f4c;
  --folio: #8a8072;
  --max: 1120px;
  --measure: 68ch;
}

[data-city="shanghai"] { --accent: #0e4f4c; }
[data-city="guangzhou"] { --accent: #8e3a2c; }

* { box-sizing: border-box; }

html {
  scroll-behavior: smooth;
}

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(180deg, rgba(26, 22, 18, 0.03), transparent 120px),
    repeating-linear-gradient(
      0deg,
      transparent,
      transparent 27px,
      rgba(26, 22, 18, 0.035) 28px
    ),
    var(--paper);
  font-family: "PingFang SC", "Hiragino Sans GB", "Noto Sans SC", "Source Han Sans SC", "Microsoft YaHei", sans-serif;
  line-height: 1.7;
  font-size: 17px;
}

a {
  color: var(--accent);
  text-underline-offset: 0.18em;
}

a:hover { text-decoration-thickness: 2px; }

.skip {
  position: absolute;
  left: -999px;
  top: 8px;
  min-height: 44px;
  min-width: 44px;
  display: inline-flex;
  align-items: center;
}

.skip:focus {
  left: 12px;
  background: var(--paper);
  padding: 10px 14px;
  z-index: 8;
}

.site-nav {
  position: sticky;
  top: 0;
  z-index: 5;
  background: rgba(243, 238, 228, 0.94);
  border-bottom: 1px solid var(--rule);
  backdrop-filter: blur(8px);
}

.site-nav__inner,
.wrap,
.article-wrap {
  width: min(var(--max), calc(100% - 40px));
  margin: 0 auto;
}

.site-nav__inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  min-height: 56px;
  font-size: 14px;
  letter-spacing: 0.04em;
}

.site-nav a {
  color: var(--ink);
  text-decoration: none;
  min-height: 44px;
  display: inline-flex;
  align-items: center;
  padding: 0 4px;
}
.site-nav a[aria-current="page"] { box-shadow: inset 0 -2px 0 var(--accent); }
.site-nav__links { display: flex; gap: 12px; flex-wrap: wrap; }

.crumb {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin: 22px 0 0;
  color: var(--ink-soft);
  font-size: 13px;
}

.crumb a { color: inherit; }

.kicker {
  margin: 18px 0 0;
  color: var(--folio);
  font-size: 12px;
  letter-spacing: 0.18em;
  text-transform: uppercase;
}

h1 {
  margin: 8px 0 12px;
  font-size: clamp(1.8rem, 3vw, 2.6rem);
  line-height: 1.25;
  font-weight: 620;
  max-width: 18em;
}

.lede, .summary {
  max-width: var(--measure);
  color: var(--ink);
}

.folio {
  color: var(--folio);
  font-size: 13px;
  font-variant-numeric: tabular-nums;
}

.preview-banner {
  margin: 18px 0;
  padding: 10px 12px;
  border: 1px dashed var(--accent);
  color: var(--accent);
  font-size: 14px;
}

.city-layout {
  display: grid;
  grid-template-columns: minmax(0, 0.9fr) minmax(0, 1.15fr);
  gap: 36px;
  align-items: start;
  margin: 18px 0 40px;
}

.city-layout--plain {
  grid-template-columns: minmax(0, 1fr);
}

.city-map {
  border: 1px solid var(--ink);
  background: var(--paper-2);
  padding: 12px;
}

.city-map--empty {
  border: none;
  background: transparent;
  padding: 0;
  max-width: 42em;
}

.city-map svg,
.diagram svg {
  display: block;
  width: 100%;
  height: auto;
  color: var(--ink);
}

.city-map [hidden],
.city-map [data-active="false"],
.map-reading-list [data-active="false"] {
  display: none;
}

.caption {
  margin: 8px 0 0;
  color: var(--ink-soft);
  font-size: 12px;
}

.filters {
  display: grid;
  grid-template-columns: 1.4fr repeat(3, 1fr) auto;
  gap: 10px;
  margin: 8px 0 18px;
  padding: 14px 0;
  border-top: 1px solid var(--rule);
  border-bottom: 1px solid var(--rule);
}

.filters label {
  display: flex;
  flex-direction: column;
  gap: 6px;
  font-size: 12px;
  color: var(--ink-soft);
}

.filters input,
.filters select,
.filters button {
  font: inherit;
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--rule);
  min-height: 44px;
  padding: 8px 10px;
}

.filters button {
  align-self: end;
  cursor: pointer;
}

.place-list {
  display: grid;
  gap: 12px;
}

.place-card {
  display: block;
  padding: 14px 0;
  border-bottom: 1px solid var(--rule-fine);
  color: inherit;
  text-decoration: none;
}

.place-card[hidden],
.empty[hidden] { display: none; }

.place-card strong {
  display: block;
  font-size: 18px;
}

.place-card span {
  color: var(--ink-soft);
  font-size: 14px;
}

.group-list {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(220px, 1fr));
  gap: 22px;
}

.group-list h3 {
  margin: 0 0 8px;
  font-size: 15px;
  border-bottom: 1px solid var(--rule);
  padding-bottom: 6px;
}

.group-list ul {
  margin: 0;
  padding-left: 1.1em;
}

.article-layout {
  display: grid;
  grid-template-columns: 180px minmax(0, 1fr);
  gap: 36px;
  margin: 20px 0 64px;
}

.toc {
  position: sticky;
  top: 72px;
  font-size: 13px;
}

.toc a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
}

#article-body h2,
#article-body section,
.catalog-block,
.visit-card,
#sources,
#questions,
#place-index,
#route-info,
#stops,
#segments,
#visit,
#observe {
  scroll-margin-top: 84px;
}

.toc ol {
  margin: 0;
  padding-left: 1.2em;
}

#article-body {
  max-width: var(--measure);
}

.visit-card {
  border: 1px solid var(--ink);
  padding: 0;
  margin: 22px 0;
}

.visit-card h2 {
  margin: 0;
  padding: 10px 14px;
  border-bottom: 1px solid var(--ink);
  font-size: 15px;
}

.visit-card dl {
  display: grid;
  grid-template-columns: 7em 1fr;
  gap: 0;
  margin: 0;
}

.visit-card dt,
.visit-card dd {
  margin: 0;
  padding: 8px 14px;
  border-bottom: 1px solid var(--rule-fine);
  font-size: 14px;
  overflow-wrap: anywhere;
  word-break: break-word;
  min-width: 0;
}

.visit-card dt { color: var(--ink-soft); }

.observe {
  counter-reset: observe;
}

.observe article {
  padding: 12px 0 16px;
  border-bottom: 1px solid var(--rule-fine);
}

.observe article::before {
  counter-increment: observe;
  content: counter(observe, decimal-leading-zero);
  display: block;
  color: var(--folio);
  font-size: 12px;
  letter-spacing: 0.12em;
  margin-bottom: 6px;
}

.fn {
  font-size: 12px;
  margin-left: 0.2em;
  text-decoration: none;
}

.sources {
  padding-left: 1.2em;
}

.related,
.footer-nav {
  margin-top: 36px;
  padding-top: 16px;
  border-top: 1px solid var(--rule);
}

.hub-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 28px;
  margin: 28px 0 48px;
}

.hub-card {
  display: block;
  padding: 22px;
  border: 1px solid var(--ink);
  color: inherit;
  text-decoration: none;
  min-height: 180px;
}

.hub-card[data-city="shanghai"] { box-shadow: inset 4px 0 0 #0e4f4c; }
.hub-card[data-city="guangzhou"] { box-shadow: inset 4px 0 0 #8e3a2c; }

.site-footer {
  border-top: 1px solid var(--rule);
  padding: 24px 0 40px;
  color: var(--ink-soft);
  font-size: 13px;
}

.info-diagram,
.observe-figure {
  margin: 22px 0;
  padding: 16px;
  border: 1px solid var(--ink);
  background: var(--paper-2);
  min-width: 0;
}

.info-diagram__mark,
.info-diagram__theme,
.info-diagram__title,
.info-diagram__node,
.info-diagram__note,
.info-diagram__edge,
.info-diagram figcaption,
.place-card span {
  overflow-wrap: anywhere;
  word-break: break-word;
}

.info-diagram__title {
  margin: 8px 0 12px;
  font-size: 17px;
}

.info-diagram__nodes,
.info-diagram__edges {
  margin: 0;
  padding-left: 1.2em;
  display: grid;
  gap: 10px;
  min-width: 0;
}

.info-diagram[data-layout="sequence"] .info-diagram__nodes,
.info-diagram[data-layout="comparison"] .info-diagram__nodes {
  grid-template-columns: repeat(auto-fit, minmax(148px, 1fr));
  padding-left: 0;
  list-style: none;
}

.info-diagram[data-layout="layers"] .info-diagram__nodes {
  grid-template-columns: 1fr;
}

.info-diagram__node {
  min-width: 0;
  padding: 10px 12px;
  border: 1px solid var(--rule);
  background: var(--paper);
}

.info-diagram__node strong,
.info-diagram__note {
  display: block;
}

.info-diagram__note {
  margin: 6px 0 0;
  color: var(--ink-soft);
  font-size: 13px;
}

.info-diagram__edges {
  margin-top: 14px;
}

.info-diagram figcaption {
  margin: 14px 0 0;
  color: var(--ink-soft);
  font-size: 13px;
}

.info-diagram svg {
  display: none;
}

.info-diagram__mark,
.info-diagram__theme {
  margin: 0 0 8px;
  color: var(--folio);
  font-size: 13px;
}

.observe-figure__mark,
.observe-figure__theme {
  margin: 0 0 8px;
  color: var(--folio);
  font-size: 13px;
}

.observe-steps {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin: 12px 0 0;
  padding: 0;
  list-style: none;
}

.observe-step {
  min-width: 0;
}

.observe-step__index {
  margin: 0 0 6px;
  color: var(--folio);
  font-size: 12px;
  letter-spacing: 0.12em;
}

.observe-step h3,
.observe-step p {
  margin: 0 0 8px;
  overflow-wrap: anywhere;
  word-break: break-word;
}

.observe-step h3 { font-size: 16px; }

.observe-figure figcaption {
  margin: 14px 0 0;
  color: var(--ink-soft);
  font-size: 13px;
}

.catalog-block { margin: 28px 0; }

.catalog-details summary,
.map-reading summary,
.visit-tech summary {
  cursor: pointer;
  min-height: 44px;
  display: flex;
  align-items: center;
  font-weight: 600;
}

.map-caption {
  margin: 0 0 10px;
  color: var(--ink-soft);
  font-size: 13px;
}

.map-toolbar {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 10px;
}

.map-toolbar button,
.empty button {
  font: inherit;
  min-height: 44px;
  min-width: 44px;
  padding: 8px 14px;
  color: var(--ink);
  background: transparent;
  border: 1px solid var(--rule);
  cursor: pointer;
}

.map-stage {
  position: relative;
}

.map-stage svg {
  touch-action: none;
  cursor: grab;
}

.map-focus {
  margin-top: 10px;
  min-height: 44px;
  display: flex;
  align-items: center;
  gap: 8px;
}

.map-focus[hidden] { display: none; }

.map-reading { margin-top: 12px; }

.map-reading-list {
  margin: 8px 0 0;
  padding-left: 1.2em;
}

.visit-tech {
  padding: 8px 14px 12px;
}

.segment-list { list-style: none; padding: 0; }
.segment-card { border: 1px solid var(--rule-fine); padding: 18px 20px; margin-bottom: 18px; }
.segment-card h3 { margin: 0 0 18px; font-size: 19px; line-height: 1.6; }
.segment-details { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 16px 24px; margin: 0; font-size: 16px; }
.segment-details > div { display: grid; grid-template-columns: 2em minmax(0, 1fr); gap: 12px; align-items: baseline; }
.segment-details dt { font-weight: 600; }
.segment-details dd { margin: 0; overflow-wrap: anywhere; }
.segment-wide { grid-column: 1 / -1; }
.filters[hidden], .map-toolbar[hidden], [data-filter-fallback][hidden] { display: none; }

@media (max-width: 1440px) {
  .info-diagram[data-layout="sequence"] .info-diagram__nodes,
  .info-diagram[data-layout="comparison"] .info-diagram__nodes {
    grid-template-columns: repeat(auto-fit, minmax(160px, 1fr));
  }
}

@media (max-width: 768px) {
  .city-layout,
  .article-layout,
  .hub-grid,
  .filters,
  .observe-steps,
  .info-diagram[data-layout="sequence"] .info-diagram__nodes,
  .info-diagram[data-layout="comparison"] .info-diagram__nodes {
    grid-template-columns: 1fr;
  }

  .city-map { order: 2; }
  .city-copy { order: 1; }
  .toc { position: static; }
  h1 { max-width: none; }
  .visit-card dl { grid-template-columns: 5.5em 1fr; }
}

@media (max-width: 390px) {
  .site-nav__inner,
  .wrap,
  .article-wrap {
    width: min(var(--max), calc(100% - 24px));
  }

  body { font-size: 16px; }
  .info-diagram,
  .visit-card,
  .place-card {
    overflow-wrap: anywhere;
    word-break: break-word;
  }
}

@media (max-width: 860px) {
  .city-layout,
  .article-layout,
  .hub-grid,
  .filters,
  .observe-steps {
    grid-template-columns: 1fr;
  }

  .city-map { order: 2; }
  .city-copy { order: 1; }
  .toc { position: static; }
  h1 { max-width: none; }
}

@media (prefers-reduced-motion: reduce) {
  html { scroll-behavior: auto; }
  *,
  *::before,
  *::after {
    animation: none !important;
    transition: none !important;
  }
}

.toc { align-self: start; }
.toc summary { cursor: pointer; min-height: 44px; padding: 10px 0; }

.info-diagram { scroll-margin-top: 84px; }

@media (max-width: 768px) {
  .segment-card { padding: 16px 14px; }
  .segment-details { grid-template-columns: minmax(0, 1fr); }
}