:root {
  --bg: #ffffff;
  --bg-soft: #f4f6f8;
  --ink: #1f2933;
  --ink-soft: #5b6b7c;
  --line: #d7dee6;
  --line-strong: #b9c4cf;
  --blue: #2f6fb0;
  --teal: #2f8f83;
  --amber: #b06a1f;
  --gray: #8a97a4;
  --radius: 6px;
  --wrap: 1120px;
  --mono: "SFMono-Regular", "Menlo", "Consolas", "Liberation Mono", monospace;
}

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

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

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

body.site-body {
  margin: 0;
  background: var(--bg);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  font-size: 15px;
  line-height: 1.7;
}

h1,
h2,
h3,
h4 {
  margin: 0;
  font-weight: 600;
  line-height: 1.35;
  color: var(--ink);
}

p {
  margin: 0;
}

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

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

a:hover,
a:focus-visible {
  text-decoration: underline;
}

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

button {
  font: inherit;
  color: inherit;
}

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

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

.headline-bar {
  background: var(--bg-soft);
  border-bottom: 1px solid var(--line);
}

.headline-bar p {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 7px 16px;
  color: var(--ink-soft);
  font-size: 13px;
}

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

.header-inner {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 16px;
  min-height: 58px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  color: var(--ink);
  font-size: 17px;
  font-weight: 600;
  white-space: nowrap;
}

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

.site-nav {
  display: flex;
  align-items: center;
}

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

.nav-list li {
  display: block;
}

.nav-list a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 12px;
  color: var(--ink-soft);
  font-size: 14px;
  border-radius: var(--radius);
}

.nav-list a:hover,
.nav-list a:focus-visible {
  color: var(--ink);
  background: var(--bg-soft);
  text-decoration: none;
}

.nav-list a.is-current {
  color: var(--blue);
  font-weight: 600;
  box-shadow: inset 0 -2px 0 var(--blue);
  border-radius: 0;
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  background: var(--bg);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 5px;
}

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

.site-main {
  display: block;
}

.home-main,
.inner-main,
.error-main {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 0 16px 56px;
}

.inner-main {
  padding-top: 18px;
}

.breadcrumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 6px;
  padding: 12px 0;
  font-size: 13px;
  color: var(--ink-soft);
}

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

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

.breadcrumb-sep {
  color: var(--gray);
}

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

.page-header {
  padding: 6px 0 22px;
  border-bottom: 1px solid var(--line);
}

.page-description {
  font-size: 13px;
  color: var(--ink-soft);
  font-family: var(--mono);
}

.page-title {
  margin-top: 8px;
  font-size: 30px;
  font-weight: 600;
  color: var(--ink);
}

.page-intro,
.page-summary {
  margin-top: 10px;
  max-width: 760px;
  color: var(--ink-soft);
}

.page-intro a,
.page-summary a {
  color: var(--blue);
}

.section,
.module,
.channel-index,
.channel-detail,
.channel-map,
.channel-boundary,
.records-stages,
.records-changes,
.records-impact,
.records-related {
  padding: 30px 0;
  border-bottom: 1px solid var(--line);
}

.section:last-child,
.records-related {
  border-bottom: 0;
}

.section-head,
.module > h2,
.channel-index > h2,
.channel-detail > h2,
.channel-map > h2,
.channel-boundary > h2,
.records-stages > h2,
.records-changes > h2,
.records-impact > h2,
.records-related > h2 {
  margin-bottom: 14px;
}

.section-head h2,
.module > h2,
.channel-index > h2,
.channel-detail > h2,
.channel-map > h2,
.channel-boundary > h2,
.records-stages > h2,
.records-changes > h2,
.records-impact > h2,
.records-related > h2 {
  font-size: 20px;
}

.section-head p,
.module-intro,
.section-note,
.section-lead,
.section-desc {
  margin-top: 6px;
  max-width: 820px;
  color: var(--ink-soft);
  font-size: 14px;
}

.section-head p a,
.module-intro a,
.section-note a,
.section-lead a,
.section-desc a {
  color: var(--blue);
}

.sub-title {
  font-size: 16px;
  margin-bottom: 10px;
}

/* ============ components ============ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
  background: var(--bg);
  cursor: pointer;
}

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

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

.btn-primary:hover,
.btn-primary:focus-visible {
  background: #275c94;
  border-color: #275c94;
  color: #ffffff;
}

.btn-ghost {
  background: var(--bg-soft);
}

.btn-ghost:hover,
.btn-ghost:focus-visible {
  background: #e8ecf1;
}

.quick-nav {
  border-bottom: 1px solid var(--line);
}

.quick-nav-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 1px;
  background: var(--line);
  border-top: 1px solid var(--line);
}

.quick-nav-list li {
  background: var(--bg-soft);
}

.quick-nav-list a {
  display: flex;
  align-items: center;
  min-height: 46px;
  padding: 0 14px;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.quick-nav-list a:hover,
.quick-nav-list a:focus-visible {
  background: #e8ecf1;
  color: var(--blue);
  text-decoration: none;
}

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

.channel-row {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 12px 10px;
  border-bottom: 1px solid var(--line);
}

.channel-row:hover {
  background: var(--bg-soft);
}

.channel-no,
.channel-code {
  flex: 0 0 auto;
  min-width: 62px;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--blue);
}

.channel-body {
  flex: 1 1 auto;
  min-width: 0;
}

.channel-name {
  font-size: 16px;
  margin-bottom: 4px;
}

.channel-scope,
.channel-field {
  font-size: 14px;
  color: var(--ink-soft);
}

.channel-field {
  margin-top: 4px;
  color: var(--amber);
}

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

.collection-card {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg);
  padding: 14px;
}

.collection-card:hover {
  border-color: var(--line-strong);
}

.collection-media {
  margin: 0 0 12px;
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-soft);
  aspect-ratio: 16 / 9;
}

.collection-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.collection-name {
  font-size: 16px;
  margin-bottom: 6px;
}

.collection-focus {
  font-size: 14px;
  color: var(--ink-soft);
}

.collection-channels,
.collection-code {
  margin-top: 8px;
  font-size: 13px;
  color: var(--teal);
  font-family: var(--mono);
}

.collection-code {
  margin: 0 0 6px;
}

.collection-body {
  display: flex;
  flex-direction: column;
}

.step-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.step-item {
  border: 1px solid var(--line);
  border-left: 3px solid var(--blue);
  border-radius: var(--radius);
  padding: 14px;
  background: var(--bg-soft);
}

.step-no {
  display: inline-block;
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--blue);
  margin-bottom: 6px;
}

.step-name {
  font-size: 15px;
  margin-bottom: 6px;
}

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

.step-field {
  margin-top: 8px;
  font-size: 13px;
  color: var(--amber);
}

.field-key {
  display: inline-block;
  margin: 0 6px 4px 0;
  padding: 1px 7px;
  border: 1px solid var(--line-strong);
  border-radius: 3px;
  background: var(--bg);
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink);
}

.fields-layout {
  display: grid;
  grid-template-columns: minmax(0, 1.6fr) minmax(0, 1fr);
  gap: 20px;
  align-items: start;
}

.fields-table-wrap,
.table-wrap,
.field-table-wrap {
  overflow-x: auto;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.field-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 14px;
}

.field-table caption,
.table-caption {
  padding: 10px 12px;
  text-align: left;
  font-size: 13px;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--line);
}

.field-table thead th {
  background: var(--bg-soft);
  text-align: left;
  font-weight: 600;
  font-size: 13px;
  color: var(--ink);
  padding: 9px 12px;
  border-bottom: 1px solid var(--line);
  white-space: nowrap;
}

.field-table tbody th,
.field-table tbody td {
  text-align: left;
  padding: 9px 12px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.field-table tbody th {
  font-weight: 600;
  font-family: var(--mono);
  font-size: 13px;
  color: var(--blue);
  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: var(--bg-soft);
}

.boundary-block {
  border: 1px solid var(--line);
  border-left: 3px solid var(--amber);
  border-radius: var(--radius);
  padding: 14px;
  background: var(--bg-soft);
}

.boundary-list {
  display: grid;
  gap: 8px;
}

.boundary-list li {
  position: relative;
  padding-left: 16px;
  font-size: 14px;
  color: var(--ink-soft);
}

.boundary-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 6px;
  background: var(--amber);
  border-radius: 1px;
}

.boundary-note {
  margin-top: 12px;
  font-size: 13px;
  color: var(--ink-soft);
}

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

.record-group {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px;
}

.record-phase {
  font-size: 15px;
  margin-bottom: 8px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
}

.record-list {
  display: grid;
  gap: 8px;
}

.record-list li {
  position: relative;
  padding-left: 14px;
  font-size: 14px;
  color: var(--ink-soft);
}

.record-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 5px;
  height: 5px;
  background: var(--gray);
  border-radius: 50%;
}

.record-tags {
  margin-top: 10px;
  padding-top: 8px;
  border-top: 1px dashed var(--line);
  font-size: 12px;
  font-family: var(--mono);
  color: var(--teal);
}

.site-index .index-list {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 12px;
}

.index-list li {
  display: flex;
  flex-direction: column;
  gap: 4px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 12px;
  background: var(--bg-soft);
}

.index-list a {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.index-list a:hover,
.index-list a:focus-visible {
  color: var(--blue);
}

.index-note {
  font-size: 12px;
  color: var(--ink-soft);
}

/* ============ pages ============ */

.hero {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1.05fr);
  gap: 28px;
  align-items: center;
  padding: 34px 0 30px;
  border-bottom: 1px solid var(--line);
}

.hero-tag {
  display: inline-block;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--teal);
  border: 1px solid var(--line-strong);
  border-radius: 3px;
  padding: 2px 8px;
}

.hero-title {
  margin-top: 12px;
  font-size: 32px;
}

.hero-desc {
  margin-top: 12px;
  max-width: 520px;
  color: var(--ink-soft);
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  margin-top: 18px;
}

.hero-visual {
  margin: 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-soft);
}

.hero-visual img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.hero-visual figcaption {
  padding: 8px 12px;
  font-size: 12px;
  color: var(--ink-soft);
  border-top: 1px solid var(--line);
}

.channel-detail .channel-block {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 16px;
  background: var(--bg);
}

.channel-detail .channel-block h3 {
  font-size: 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 10px;
}

.channel-figure {
  margin: 0 0 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-soft);
  max-width: 620px;
}

.channel-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.channel-figure figcaption {
  padding: 7px 12px;
  font-size: 12px;
  color: var(--ink-soft);
  border-top: 1px solid var(--line);
}

.channel-block-scope {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 10px;
}

.field-list {
  display: grid;
  grid-template-columns: minmax(120px, 160px) minmax(0, 1fr);
  gap: 0;
  border-top: 1px solid var(--line);
}

.field-list dt {
  padding: 8px 10px;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--blue);
  border-bottom: 1px solid var(--line);
  background: var(--bg-soft);
}

.field-list dd {
  margin: 0;
  padding: 8px 10px;
  font-size: 14px;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--line);
}

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

.map-col {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px;
}

.map-col h3 {
  font-size: 15px;
  margin-bottom: 8px;
}

.map-list {
  display: grid;
  gap: 6px;
}

.map-list li {
  display: flex;
  align-items: center;
  gap: 10px;
  font-size: 14px;
  color: var(--ink-soft);
  border-bottom: 1px dashed var(--line);
  padding-bottom: 6px;
}

.map-list li:last-child {
  border-bottom: 0;
  padding-bottom: 0;
}

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

.basis-item {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px;
}

.basis-name {
  font-size: 15px;
  margin-bottom: 10px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
}

.basis-fields {
  display: grid;
  grid-template-columns: minmax(96px, 130px) minmax(0, 1fr);
}

.basis-fields dt {
  padding: 6px 8px;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--teal);
  background: var(--bg-soft);
  border-bottom: 1px solid var(--line);
}

.basis-fields dd {
  margin: 0;
  padding: 6px 8px;
  font-size: 14px;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--line);
}

.advice-list {
  counter-reset: advice;
  display: grid;
  gap: 12px;
}

.advice-item {
  counter-increment: advice;
  position: relative;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px 14px 14px 52px;
}

.advice-item::before {
  content: counter(advice, decimal-leading-zero);
  position: absolute;
  left: 14px;
  top: 14px;
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--teal);
}

.advice-title {
  font-size: 15px;
  margin-bottom: 6px;
}

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

.steps-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 14px;
}

.step-card {
  border: 1px solid var(--line);
  border-top: 3px solid var(--line-strong);
  border-radius: var(--radius);
  padding: 14px;
  background: var(--bg-soft);
}

.step-card.step-1 {
  border-top-color: var(--blue);
}

.step-card.step-2 {
  border-top-color: var(--teal);
}

.step-card.step-3 {
  border-top-color: var(--amber);
}

.step-card.step-4 {
  border-top-color: var(--gray);
}

.step-index {
  font-family: var(--mono);
  font-size: 12px;
  font-weight: 600;
  color: var(--ink-soft);
  margin-bottom: 6px;
}

.step-card .step-name {
  font-size: 15px;
  margin-bottom: 6px;
}

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

.step-card .step-field {
  margin-top: 10px;
  padding-top: 8px;
  border-top: 1px dashed var(--line-strong);
}

.section-figure {
  margin: 20px 0 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-soft);
}

.section-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 21 / 9;
  object-fit: cover;
}

.section-figure figcaption {
  padding: 8px 12px;
  font-size: 12px;
  color: var(--ink-soft);
  border-top: 1px solid var(--line);
}

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

.check-item {
  border: 1px solid var(--line);
  border-left: 3px solid var(--blue);
  border-radius: var(--radius);
  padding: 14px;
}

.check-name {
  font-size: 15px;
  margin-bottom: 6px;
}

.check-body {
  font-size: 14px;
  color: var(--ink-soft);
}

.faq-list {
  display: grid;
  gap: 10px;
}

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

.faq-question {
  cursor: pointer;
  padding: 12px 40px 12px 14px;
  position: relative;
  font-size: 15px;
  font-weight: 600;
  min-height: 44px;
  display: flex;
  align-items: center;
}

.faq-question::-webkit-details-marker {
  display: none;
}

.faq-question::after {
  content: "+";
  position: absolute;
  right: 14px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--mono);
  font-size: 16px;
  color: var(--ink-soft);
}

.faq-item[open] .faq-question::after {
  content: "−";
}

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

.faq-answer {
  padding: 12px 14px;
}

.faq-answer p {
  font-size: 14px;
  color: var(--ink-soft);
}

.next-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.next-item a {
  display: flex;
  align-items: center;
  min-height: 46px;
  padding: 10px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--bg-soft);
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

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

.page-media {
  margin: 20px 0 0;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  background: var(--bg-soft);
}

.page-media img {
  width: 100%;
  height: auto;
  aspect-ratio: 21 / 8;
  object-fit: cover;
}

.page-media figcaption {
  padding: 8px 12px;
  font-size: 12px;
  color: var(--ink-soft);
  border-top: 1px solid var(--line);
}

.stage-group {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  margin-bottom: 16px;
}

.stage-head {
  display: flex;
  flex-wrap: wrap;
  align-items: baseline;
  justify-content: space-between;
  gap: 8px;
  padding-bottom: 10px;
  margin-bottom: 10px;
  border-bottom: 1px solid var(--line);
}

.stage-name {
  font-size: 16px;
}

.stage-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.stage-date {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-soft);
  border: 1px solid var(--line);
  border-radius: 3px;
  padding: 1px 7px;
}

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

.stage-item {
  border-left: 2px solid var(--line-strong);
  padding-left: 12px;
}

.stage-text {
  font-size: 14px;
}

.stage-refs {
  margin-top: 6px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 13px;
  font-family: var(--mono);
}

.stage-refs a {
  color: var(--teal);
}

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

.impact-item {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 14px;
  background: var(--bg-soft);
}

.impact-name {
  font-size: 15px;
  margin-bottom: 6px;
}

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

.related-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 12px;
}

.related-item a {
  display: flex;
  align-items: center;
  min-height: 46px;
  padding: 10px 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

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

.error-main {
  padding-top: 40px;
}

.error-panel {
  border: 1px solid var(--line);
  border-left: 3px solid var(--amber);
  border-radius: var(--radius);
  padding: 24px;
  background: var(--bg-soft);
  max-width: 760px;
}

.error-code {
  font-family: var(--mono);
  font-size: 13px;
  font-weight: 600;
  color: var(--amber);
}

.error-title {
  margin-top: 8px;
  font-size: 28px;
}

.error-desc {
  margin-top: 10px;
  color: var(--ink-soft);
}

.error-links {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin-top: 18px;
}

.error-links a {
  display: flex;
  align-items: center;
  min-height: 44px;
  padding: 8px 14px;
  border: 1px solid var(--line-strong);
  border-radius: var(--radius);
  background: var(--bg);
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

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

.error-note {
  margin-top: 16px;
  font-size: 13px;
  color: var(--ink-soft);
}

/* ============ footer ============ */

.site-footer {
  background: var(--bg-soft);
  border-top: 1px solid var(--line);
  margin-top: 24px;
}

.footer-inner {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 30px 16px 24px;
  display: grid;
  grid-template-columns: minmax(0, 1.4fr) repeat(4, minmax(0, 1fr));
  gap: 24px;
}

.footer-brand {
  min-width: 0;
}

.footer-name {
  font-size: 16px;
  font-weight: 600;
  color: var(--ink);
}

.footer-desc {
  margin-top: 8px;
  font-size: 13px;
  color: var(--ink-soft);
}

.footer-back {
  margin-top: 12px;
  font-size: 13px;
}

.footer-back a {
  color: var(--blue);
}

.footer-col-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 10px;
}

.footer-col ul {
  display: grid;
  gap: 8px;
}

.footer-col a {
  font-size: 13px;
  color: var(--ink-soft);
}

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

.footer-bottom {
  border-top: 1px solid var(--line);
}

.footer-bottom p {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 14px 16px;
  font-size: 12px;
  color: var(--ink-soft);
}

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

@media (max-width: 900px) {
  .hero {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px;
  }

  .hero-title {
    font-size: 28px;
  }

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

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

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

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

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

  .footer-brand {
    grid-column: 1 / -1;
  }
}

@media (max-width: 768px) {
  .site-header {
    position: sticky;
  }

  .header-inner {
    flex-wrap: wrap;
    padding-top: 6px;
    padding-bottom: 6px;
  }

  .nav-toggle {
    display: flex;
    order: 2;
  }

  .site-nav {
    order: 3;
    width: 100%;
    display: block;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 6px 0 10px;
    border-top: 1px solid var(--line);
  }

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

  .nav-list a {
    min-height: 46px;
    padding: 0 6px;
    border-radius: 0;
    border-bottom: 1px solid var(--line);
  }

  .nav-list a.is-current {
    box-shadow: none;
    background: var(--bg-soft);
    border-radius: var(--radius);
  }

  .page-title {
    font-size: 22px;
  }

  .hero-title {
    font-size: 22px;
  }

  .section-head h2,
  .module > h2,
  .channel-index > h2,
  .channel-detail > h2,
  .channel-map > h2,
  .channel-boundary > h2,
  .records-stages > h2,
  .records-changes > h2,
  .records-impact > h2,
  .records-related > h2 {
    font-size: 17px;
  }

  .quick-nav-list {
    display: flex;
    overflow-x: auto;
    -webkit-overflow-scrolling: touch;
  }

  .quick-nav-list li {
    flex: 0 0 auto;
    min-width: 140px;
  }

  .collection-grid,
  .basis-list,
  .check-list,
  .impact-list,
  .map-columns {
    grid-template-columns: minmax(0, 1fr);
  }

  .step-list,
  .steps-grid,
  .next-list,
  .related-list,
  .error-links {
    grid-template-columns: minmax(0, 1fr);
  }

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

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

  .channel-row {
    flex-direction: column;
    gap: 6px;
  }

  .channel-no,
  .channel-code {
    min-width: 0;
  }

  .field-list,
  .basis-fields {
    grid-template-columns: minmax(0, 1fr);
  }

  .field-list dt,
  .basis-fields dt {
    border-bottom: 0;
    padding-bottom: 2px;
  }

  .field-list dd,
  .basis-fields dd {
    padding-top: 0;
  }

  .footer-inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 20px;
  }
}

@media (max-width: 480px) {
  .headline-bar p {
    font-size: 12px;
  }

  .hero {
    padding: 22px 0 20px;
  }

  .page-header {
    padding-bottom: 16px;
  }

  .section,
  .module,
  .channel-index,
  .channel-detail,
  .channel-map,
  .channel-boundary,
  .records-stages,
  .records-changes,
  .records-impact,
  .records-related {
    padding: 22px 0;
  }

  .error-panel {
    padding: 18px;
  }

  .error-title {
    font-size: 22px;
  }
}