:root {
  --paper: #f6f3ec;
  --ink: #1f2a37;
  --ink-soft: #4b5765;
  --ink-faint: #7b8593;
  --blue: #3d5a80;
  --blue-deep: #2c4463;
  --seal: #a8442c;
  --line: #d8d2c4;
  --line-strong: #b9b2a0;
  --card: #ffffff;
  --radius: 6px;
  --radius-sm: 4px;
  --wrap: 1080px;
  --serif: "Songti SC", "STSong", SimSun, "Noto Serif SC", serif;
  --sans: "PingFang SC", "Microsoft YaHei", "Hiragino Sans GB", Arial, sans-serif;
  --mono: ui-monospace, Menlo, Consolas, "Courier New", monospace;
}

/* ============ base ============ */

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 16px;
  line-height: 1.8;
}

h1,
h2,
h3,
h4 {
  margin: 0;
  font-family: var(--serif);
  font-weight: 700;
  color: var(--ink);
}

h1 {
  font-size: 32px;
  line-height: 1.35;
}

h2 {
  font-size: 22px;
  line-height: 1.4;
}

h3 {
  font-size: 17px;
  line-height: 1.5;
}

p {
  margin: 0 0 14px;
}

p:last-child {
  margin-bottom: 0;
}

ul,
ol {
  margin: 0;
  padding: 0;
  list-style: none;
}

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

a:hover,
a:focus-visible {
  color: var(--seal);
  text-decoration: underline;
}

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

table {
  border-collapse: collapse;
  width: 100%;
}

:focus-visible {
  outline: 2px solid var(--blue);
  outline-offset: 2px;
}

.visually-hidden {
  position: absolute;
  width: 1px;
  height: 1px;
  margin: -1px;
  padding: 0;
  overflow: hidden;
  clip: rect(0 0 0 0);
  white-space: nowrap;
  border: 0;
}

.skip-link {
  position: absolute;
  left: 12px;
  top: -60px;
  z-index: 40;
  padding: 10px 16px;
  background-color: var(--blue);
  color: #fff;
  border-radius: var(--radius-sm);
  transition: top 0.15s ease;
}

.skip-link:focus {
  top: 12px;
  color: #fff;
  text-decoration: none;
}

/* ============ layout ============ */

.site-body {
  display: flex;
  flex-direction: column;
  min-height: 100vh;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 30;
  background-color: var(--paper);
  border-bottom: 1px solid var(--line);
}

.header-inner {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 10px 24px;
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 14px 24px;
}

.site-main {
  flex: 1 1 auto;
  width: 100%;
}

.home-main {
  display: block;
}

.inner-main {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 26px 24px 56px;
}

.site-footer {
  margin-top: auto;
  background-color: #efeae0;
  border-top: 1px solid var(--line);
}

.footer-inner {
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 28px 32px;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 40px 24px 26px;
}

.footer-copy {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 14px 24px 26px;
  border-top: 1px solid var(--line);
  color: var(--ink-faint);
  font-size: 13px;
}

/* ============ components: brand & nav ============ */

.brand {
  display: flex;
  align-items: baseline;
  gap: 10px;
  color: var(--ink);
  text-decoration: none;
}

.brand:hover,
.brand:focus-visible {
  color: var(--ink);
  text-decoration: none;
}

.brand-mark {
  font-family: var(--serif);
  font-size: 24px;
  font-weight: 700;
  line-height: 1.2;
}

.brand-sub {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--seal);
}

.nav-toggle {
  display: none;
  align-items: center;
  gap: 8px;
  min-height: 44px;
  padding: 8px 14px;
  margin-left: auto;
  background-color: var(--card);
  border: 1px solid var(--line-strong);
  border-radius: var(--radius-sm);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 14px;
  cursor: pointer;
}

.nav-toggle-icon {
  display: block;
  width: 18px;
  height: 2px;
  background-color: var(--ink);
  position: relative;
}

.nav-toggle-icon::before,
.nav-toggle-icon::after {
  content: "";
  position: absolute;
  left: 0;
  width: 18px;
  height: 2px;
  background-color: var(--ink);
}

.nav-toggle-icon::before {
  top: -6px;
}

.nav-toggle-icon::after {
  top: 6px;
}

.site-nav {
  margin-left: auto;
}

.nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
}

.nav-list li {
  display: block;
}

.nav-list a {
  display: inline-block;
  padding: 8px 14px;
  min-height: 44px;
  line-height: 28px;
  color: var(--ink-soft);
  font-size: 15px;
  border-radius: var(--radius-sm);
  border-bottom: 2px solid transparent;
}

.nav-list a:hover,
.nav-list a:focus-visible {
  color: var(--blue-deep);
  background-color: #ffffff;
  text-decoration: none;
}

.nav-list a.is-current {
  color: var(--blue-deep);
  font-weight: 700;
  border-bottom-color: var(--seal);
}

/* ============ components: section head ============ */

.section-head {
  margin-bottom: 22px;
}

.section-index {
  display: inline-block;
  margin-bottom: 8px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.12em;
  color: var(--seal);
}

.section-desc,
.section-lead,
.section-note {
  margin: 8px 0 0;
  color: var(--ink-soft);
  font-size: 15px;
}

.section-foot {
  margin: 20px 0 0;
  font-size: 14px;
}

.section-foot a {
  font-weight: 600;
}

/* ============ components: buttons ============ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 10px 20px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--blue);
  font-size: 15px;
  font-weight: 600;
  text-decoration: none;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
}

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

.btn-primary:hover,
.btn-primary:focus-visible {
  background-color: var(--blue-deep);
  border-color: var(--blue-deep);
  color: #ffffff;
  text-decoration: none;
}

.btn-ghost {
  background-color: transparent;
  color: var(--blue-deep);
}

.btn-ghost:hover,
.btn-ghost:focus-visible {
  background-color: #ffffff;
  border-color: var(--blue-deep);
  color: var(--blue-deep);
  text-decoration: none;
}

/* ============ components: tables ============ */

.table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background-color: var(--card);
}

.field-table {
  min-width: 560px;
  font-size: 15px;
}

.field-table caption {
  text-align: left;
}

.field-table th,
.field-table td {
  padding: 12px 16px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}

.field-table thead th {
  background-color: #f1ece1;
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.06em;
  color: var(--blue-deep);
  white-space: nowrap;
}

.field-table tbody th {
  width: 22%;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--seal);
  white-space: nowrap;
}

.field-table tbody tr:last-child th,
.field-table tbody tr:last-child td {
  border-bottom: 0;
}

.field-table tbody tr:hover {
  background-color: #faf7f0;
}

.legend-table {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background-color: var(--card);
  font-size: 15px;
}

.legend-table .table-caption {
  padding: 12px 16px;
  text-align: left;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.08em;
  color: var(--ink-faint);
  border-bottom: 1px solid var(--line);
}

.legend-table th,
.legend-table td {
  padding: 12px 16px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--line);
}

.legend-table thead th {
  background-color: #f1ece1;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--blue-deep);
  white-space: nowrap;
}

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

/* ============ components: marks & tags ============ */

.mark {
  display: inline-block;
  padding: 2px 8px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--line-strong);
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  white-space: nowrap;
  background-color: #ffffff;
  color: var(--ink-soft);
}

.mark-new {
  border-color: var(--seal);
  color: var(--seal);
}

.mark-move {
  border-color: var(--blue);
  color: var(--blue-deep);
}

.mark-index {
  border-color: #6d7f5b;
  color: #4d5c3e;
}

.mark-fix {
  border-color: #8a6d3b;
  color: #7a5c2c;
}

.mark-scope {
  border-color: var(--line-strong);
  color: var(--ink-faint);
}

/* ============ components: breadcrumb & page header ============ */

.breadcrumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  margin-bottom: 18px;
  font-size: 13px;
  color: var(--ink-faint);
}

.breadcrumb a {
  color: var(--ink-soft);
}

.breadcrumb-sep {
  font-family: var(--mono);
  color: var(--line-strong);
}

.breadcrumb-current {
  color: var(--ink);
}

.page-header {
  margin-bottom: 34px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}

.page-title {
  font-size: 32px;
  line-height: 1.35;
}

.page-description,
.page-summary {
  margin: 12px 0 0;
  max-width: 720px;
  color: var(--ink-soft);
  font-size: 16px;
}

/* ============ components: footer ============ */

.footer-brand-name {
  margin-bottom: 8px;
  font-family: var(--serif);
  font-size: 19px;
  font-weight: 700;
}

.footer-desc {
  margin: 0;
  max-width: 320px;
  color: var(--ink-soft);
  font-size: 14px;
}

.footer-title {
  margin-bottom: 10px;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--seal);
}

.footer-group ul li {
  margin-bottom: 6px;
}

.footer-group a {
  display: inline-block;
  min-height: 32px;
  line-height: 32px;
  color: var(--ink-soft);
  font-size: 14px;
}

.footer-group a:hover,
.footer-group a:focus-visible {
  color: var(--blue-deep);
}

/* ============ pages: home hero ============ */

.hero {
  border-bottom: 1px solid var(--line);
  background-color: #fbf9f4;
}

.hero-inner {
  display: grid;
  grid-template-columns: minmax(0, 1.15fr) minmax(0, 1fr);
  align-items: start;
  gap: 40px;
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 48px 24px 32px;
}

.hero-text {
  min-width: 0;
}

.hero-eyebrow {
  margin-bottom: 12px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  color: var(--seal);
}

.hero-title {
  font-size: 32px;
  line-height: 1.35;
}

.hero-summary {
  margin: 16px 0 0;
  max-width: 560px;
  color: var(--ink-soft);
  font-size: 16px;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.hero-quicklinks {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 26px;
  padding-top: 20px;
  border-top: 1px dashed var(--line-strong);
}

.hero-quicklinks a {
  display: inline-block;
  min-height: 36px;
  padding: 6px 14px;
  line-height: 22px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--blue-deep);
}

.hero-quicklinks a:hover,
.hero-quicklinks a:focus-visible {
  border-color: var(--blue);
  text-decoration: none;
}

.hero-figure {
  margin: 0;
  padding: 10px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.hero-figure img {
  width: 100%;
  aspect-ratio: 4 / 3;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.hero-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-faint);
}

.hero-path-note {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 24px 26px;
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.04em;
  color: var(--ink-faint);
}

/* ============ pages: home sections ============ */

.topics-overview,
.fields-overview,
.records-overview,
.boundary-overview,
.site-index,
.media-note {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 44px 24px 0;
}

.topics-overview {
  padding-top: 48px;
}

.topic-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 20px;
}

.topic-col {
  padding: 18px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.topic-col:hover {
  border-color: var(--line-strong);
  transform: translateY(-2px);
}

.topic-no {
  margin-bottom: 8px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--seal);
}

.topic-name {
  margin-bottom: 8px;
}

.topic-desc {
  margin-bottom: 14px;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.75;
}

.topic-samples {
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

.topic-samples li {
  display: flex;
  flex-direction: column;
  gap: 2px;
  margin-bottom: 10px;
}

.topic-samples li:last-child {
  margin-bottom: 0;
}

.sample-name,
.sample-title {
  font-size: 14px;
  color: var(--ink);
}

.sample-meta,
.sample-fields {
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.04em;
  color: var(--ink-faint);
}

.record-list {
  border-top: 1px solid var(--line);
}

.record-row {
  display: grid;
  grid-template-columns: 130px minmax(0, 1.6fr) minmax(0, 1fr);
  gap: 16px;
  align-items: baseline;
  padding: 14px 4px;
  border-bottom: 1px solid var(--line);
}

.record-date {
  font-family: var(--mono);
  font-size: 13px;
  color: var(--seal);
}

.record-action {
  font-size: 15px;
}

.record-topic {
  font-size: 13px;
  color: var(--ink-faint);
}

.boundary-columns {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.boundary-scope,
.boundary-feedback {
  padding: 20px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.col-title {
  margin-bottom: 12px;
  font-size: 16px;
}

.scope-list li {
  position: relative;
  padding-left: 18px;
  margin-bottom: 8px;
  font-size: 14px;
  color: var(--ink-soft);
}

.scope-list li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--line-strong);
}

.feedback-link {
  margin-top: 12px;
  font-size: 14px;
  font-weight: 600;
}

.index-bar {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 14px;
}

.index-item {
  padding: 16px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.index-item:hover {
  border-color: var(--blue);
  transform: translateY(-2px);
}

.index-item a {
  display: block;
  font-family: var(--serif);
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
}

.index-note {
  display: block;
  margin-top: 6px;
  font-size: 13px;
  color: var(--ink-faint);
}

.media-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.media-item {
  margin: 0;
  padding: 10px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.media-item img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.media-item figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-faint);
}

/* ============ pages: topics ============ */

.page-topics .topic-catalog,
.page-topics .topic-orientation,
.page-topics .topic-scope,
.page-topics .topic-related {
  margin-bottom: 44px;
}

.page-topics .topic-catalog > h2,
.page-topics .topic-orientation > h2,
.page-topics .topic-scope > h2,
.page-topics .topic-related > h2 {
  margin-bottom: 8px;
}

.page-topics .topic-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  margin-top: 22px;
}

.topic-card {
  padding: 20px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-left: 3px solid var(--blue);
  border-radius: var(--radius);
  scroll-margin-top: 90px;
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.topic-card:hover {
  border-color: var(--line-strong);
  border-left-color: var(--seal);
  transform: translateY(-2px);
}

.topic-card .topic-no {
  display: block;
  margin-bottom: 6px;
  font-family: var(--mono);
  font-size: 12px;
  letter-spacing: 0.1em;
  color: var(--seal);
}

.topic-card .topic-name {
  margin-bottom: 10px;
}

.topic-intro {
  margin-bottom: 14px;
  color: var(--ink-soft);
  font-size: 14px;
  line-height: 1.75;
}

.topic-samples .topic-sample {
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  gap: 4px 12px;
  padding: 8px 0;
  border-top: 1px dashed var(--line);
}

.orientation-layout {
  display: grid;
  grid-template-columns: minmax(0, 0.85fr) minmax(0, 1.15fr);
  gap: 28px;
  margin-top: 22px;
  align-items: start;
}

.orientation-media {
  margin: 0;
  padding: 10px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.orientation-media img {
  width: 100%;
  aspect-ratio: 3 / 4;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.orientation-media figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-faint);
}

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

.orientation-item {
  padding: 16px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.orientation-item h3 {
  margin-bottom: 6px;
  font-size: 16px;
}

.orientation-item p {
  margin: 0;
  font-size: 14px;
  color: var(--ink-soft);
}

.scope-list {
  margin-top: 8px;
}

.topic-scope .scope-item {
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.topic-scope .scope-item:first-child {
  border-top: 1px solid var(--line);
}

.topic-scope .scope-item h3 {
  margin-bottom: 6px;
  font-size: 16px;
}

.topic-scope .scope-item p {
  margin: 0;
  max-width: 720px;
  color: var(--ink-soft);
  font-size: 14px;
}

.related-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
  margin-top: 22px;
}

.related-item,
.related-card,
.related-cell {
  padding: 18px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  transition: border-color 0.15s ease, transform 0.15s ease;
}

.related-item:hover,
.related-card:hover,
.related-cell:hover {
  border-color: var(--blue);
  transform: translateY(-2px);
}

.related-item h3,
.related-card-title,
.related-name {
  margin-bottom: 8px;
  font-size: 16px;
}

.related-item p,
.related-card-desc,
.related-text,
.related-desc {
  margin: 0;
  font-size: 14px;
  color: var(--ink-soft);
}

/* ============ pages: guide ============ */

.page-guide .page-layout {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: 36px;
  align-items: start;
}

.sidebar-left .page-layout {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: 36px;
  align-items: start;
}

.guide-aside {
  position: sticky;
  top: 84px;
  padding: 18px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.aside-title {
  margin-bottom: 12px;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.1em;
  color: var(--seal);
}

.topic-tree li {
  margin-bottom: 4px;
}

.topic-tree a {
  display: block;
  min-height: 40px;
  padding: 8px 10px;
  line-height: 24px;
  border-radius: var(--radius-sm);
  font-size: 14px;
  color: var(--ink-soft);
}

.topic-tree a:hover,
.topic-tree a:focus-visible {
  background-color: #f1ece1;
  color: var(--blue-deep);
  text-decoration: none;
}

.content-column {
  min-width: 0;
}

.guide-section {
  margin-bottom: 44px;
  scroll-margin-top: 90px;
}

.guide-section > h2 {
  margin-bottom: 8px;
}

.guide-figure {
  margin: 18px 0;
  padding: 10px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.guide-figure img {
  width: 100%;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.guide-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-faint);
}

.content-column .field-table {
  min-width: 0;
}

.path-steps {
  margin-top: 18px;
  counter-reset: path;
}

.path-step {
  display: grid;
  grid-template-columns: 44px minmax(0, 1fr);
  gap: 4px 14px;
  padding: 16px 0;
  border-bottom: 1px solid var(--line);
}

.path-step:first-child {
  border-top: 1px solid var(--line);
}

.step-no {
  grid-row: span 2;
  font-family: var(--mono);
  font-size: 20px;
  color: var(--line-strong);
}

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

.path-step p {
  margin: 0;
  max-width: 640px;
  font-size: 14px;
  color: var(--ink-soft);
}

.faq-item {
  border-bottom: 1px solid var(--line);
}

.faq-item:first-of-type {
  border-top: 1px solid var(--line);
}

.faq-item summary {
  display: flex;
  align-items: center;
  min-height: 48px;
  padding: 12px 4px;
  font-family: var(--serif);
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
}

.faq-item summary::marker {
  color: var(--seal);
}

.faq-item p {
  margin: 0 0 14px;
  max-width: 720px;
  padding-left: 4px;
  font-size: 15px;
  color: var(--ink-soft);
}

.related-links {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 16px;
  margin-top: 18px;
}

.guide-related .related-item {
  padding: 16px;
}

.guide-related .related-item a {
  font-weight: 600;
}

/* ============ pages: records ============ */

.page-records .records-legend,
.page-records .records-timeline,
.page-records .records-order,
.page-records .related-links {
  margin-bottom: 44px;
}

.section-title {
  margin-bottom: 8px;
}

.section-title .section-index {
  display: block;
  margin-bottom: 6px;
}

.records-timeline .records-figure {
  margin: 20px 0 26px;
  padding: 10px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.records-figure img {
  width: 100%;
  aspect-ratio: 21 / 9;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.records-figure figcaption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-faint);
}

.group-title {
  margin: 26px 0 10px;
  padding-bottom: 6px;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  letter-spacing: 0.08em;
  color: var(--blue-deep);
  border-bottom: 1px solid var(--line);
}

.records-timeline .record-list {
  border-top: 0;
}

.record-item {
  display: grid;
  grid-template-columns: 120px 96px minmax(0, 1fr);
  gap: 6px 16px;
  align-items: baseline;
  padding: 14px 4px;
  border-bottom: 1px solid var(--line);
}

.record-text {
  margin: 0;
  font-size: 15px;
}

.record-scope {
  grid-column: 3;
  font-size: 13px;
  color: var(--ink-faint);
}

.records-order p {
  max-width: 720px;
  color: var(--ink-soft);
  font-size: 15px;
}

/* ============ pages: boundary ============ */

.page-boundary .section {
  margin-bottom: 44px;
}

.section-scope .scope-columns {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.scope-block {
  padding: 20px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.scope-in {
  border-top: 3px solid var(--blue);
}

.scope-out {
  border-top: 3px solid var(--seal);
}

.scope-title {
  margin-bottom: 12px;
  font-size: 16px;
}

.scope-figure {
  margin: 24px 0 0;
  padding: 10px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.scope-figure img {
  width: 100%;
  aspect-ratio: 21 / 9;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.scope-figure .figure-caption {
  margin-top: 10px;
  font-size: 13px;
  color: var(--ink-faint);
}

.basis-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
}

.basis-item {
  padding: 18px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.basis-name {
  margin-bottom: 8px;
  font-size: 16px;
}

.basis-text {
  margin: 0;
  font-size: 14px;
  color: var(--ink-soft);
}

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

.feedback-step {
  padding: 18px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.step-index {
  display: inline-block;
  margin-bottom: 8px;
  font-family: var(--mono);
  font-size: 13px;
  letter-spacing: 0.1em;
  color: var(--seal);
}

.step-name {
  margin-bottom: 8px;
  font-size: 16px;
}

.step-text {
  margin: 0;
  font-size: 14px;
  color: var(--ink-soft);
}

.feedback-entry {
  margin-top: 22px;
  padding: 20px;
  background-color: #fbf9f4;
  border: 1px solid var(--line);
  border-left: 3px solid var(--blue);
  border-radius: var(--radius);
}

.feedback-entry-text {
  max-width: 720px;
  color: var(--ink-soft);
  font-size: 15px;
}

.feedback-entry-links {
  display: flex;
  flex-wrap: wrap;
  gap: 12px 24px;
  margin: 10px 0 0;
}

.text-link {
  font-weight: 600;
}

.section-related .related-columns {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
}

/* ============ pages: 404 ============ */

.error-main {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 56px 24px 72px;
}

.error-block {
  max-width: 720px;
  padding: 32px;
  background-color: var(--card);
  border: 1px solid var(--line);
  border-left: 3px solid var(--seal);
  border-radius: var(--radius);
}

.error-code {
  margin-bottom: 10px;
  font-family: var(--mono);
  font-size: 14px;
  letter-spacing: 0.16em;
  color: var(--seal);
}

.error-desc {
  margin: 12px 0 0;
  color: var(--ink-soft);
}

.error-reasons {
  margin: 20px 0 0;
  padding-top: 16px;
  border-top: 1px solid var(--line);
}

.error-reasons li {
  position: relative;
  padding-left: 18px;
  margin-bottom: 8px;
  font-size: 14px;
  color: var(--ink-soft);
}

.error-reasons li::before {
  content: "—";
  position: absolute;
  left: 0;
  color: var(--line-strong);
}

.error-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  margin-top: 24px;
}

.error-note {
  margin: 20px 0 0;
  padding-top: 16px;
  border-top: 1px dashed var(--line-strong);
  font-size: 14px;
  color: var(--ink-soft);
}

.error-note a {
  margin-right: 16px;
}

/* ============ responsive ============ */

@media (max-width: 1024px) {
  .hero-inner {
    grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
    gap: 28px;
  }

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

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

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

  .page-guide .page-layout,
  .sidebar-left .page-layout {
    grid-template-columns: 200px minmax(0, 1fr);
    gap: 26px;
  }
}

@media (max-width: 768px) {
  .nav-toggle {
    display: inline-flex;
  }

  .site-nav {
    flex-basis: 100%;
    margin-left: 0;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
    padding: 6px 0 12px;
    border-top: 1px solid var(--line);
  }

  .nav-list.is-open {
    display: flex;
  }

  .nav-list a {
    display: block;
    padding: 10px 6px;
    border-bottom: 1px solid var(--line);
    border-radius: 0;
  }

  .nav-list a.is-current {
    border-bottom-color: var(--line);
    border-left: 3px solid var(--seal);
    padding-left: 12px;
  }

  .hero-inner {
    grid-template-columns: minmax(0, 1fr);
    padding-top: 32px;
  }

  .hero-title,
  .page-title {
    font-size: 27px;
  }

  .topic-grid,
  .media-grid,
  .boundary-columns,
  .orientation-list,
  .basis-list,
  .feedback-steps,
  .related-grid,
  .related-links,
  .section-related .related-columns,
  .section-scope .scope-columns {
    grid-template-columns: minmax(0, 1fr);
  }

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

  .orientation-media img {
    aspect-ratio: 16 / 9;
  }

  .page-guide .page-layout,
  .sidebar-left .page-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 28px;
  }

  .guide-aside {
    position: static;
    order: 2;
  }

  .content-column {
    order: 1;
  }

  .record-row {
    grid-template-columns: minmax(0, 1fr);
    gap: 4px;
  }

  .record-item {
    grid-template-columns: minmax(0, 1fr);
    gap: 6px;
  }

  .record-scope {
    grid-column: auto;
  }

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

  .footer-inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 22px;
  }
}

@media (max-width: 480px) {
  body {
    font-size: 15px;
  }

  h1 {
    font-size: 24px;
  }

  h2 {
    font-size: 20px;
  }

  .header-inner,
  .inner-main,
  .hero-inner,
  .hero-path-note,
  .topics-overview,
  .fields-overview,
  .records-overview,
  .boundary-overview,
  .site-index,
  .media-note,
  .error-main,
  .footer-inner,
  .footer-copy {
    padding-left: 16px;
    padding-right: 16px;
  }

  .hero-title,
  .page-title {
    font-size: 23px;
  }

  .hero-actions .btn,
  .error-actions .btn {
    width: 100%;
  }

  .error-block {
    padding: 22px 18px;
  }

  .index-bar {
    grid-template-columns: minmax(0, 1fr);
  }

  .topic-col,
  .topic-card,
  .orientation-item,
  .basis-item,
  .feedback-step,
  .related-item,
  .related-card,
  .related-cell,
  .boundary-scope,
  .boundary-feedback,
  .scope-block {
    padding: 16px;
  }
}

@media (prefers-reduced-motion: reduce) {
  * {
    transition-duration: 0.01ms !important;
  }
}