:root {
  --paper: #F6F1E7;
  --ink: #2E2A24;
  --ink-soft: #5A5347;
  --ochre: #A65A2E;
  --ochre-dark: #8A4823;
  --moss: #6B7A5A;
  --rule: #D9CFBC;
  --rule-soft: #E6DECE;
  --card: #FBF8F1;
  --shadow: 0 1px 2px rgba(46, 42, 36, 0.06);
  --radius: 6px;
  --maxw: 1120px;
  --readw: 720px;
  --font-sans: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", "Noto Sans CJK SC", system-ui, -apple-system, "Segoe UI", sans-serif;
  --font-mono: "SFMono-Regular", "JetBrains Mono", Consolas, "Liberation Mono", Menlo, monospace;
}

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

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

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

body {
  margin: 0;
  background-color: var(--paper);
  color: var(--ink);
  font-family: var(--font-sans);
  font-size: 16px;
  line-height: 1.75;
  font-weight: 400;
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  margin: 0;
  color: var(--ink);
  font-weight: 700;
  line-height: 1.35;
  letter-spacing: 0.01em;
}

p {
  margin: 0;
}

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

a {
  color: var(--ochre);
  text-decoration: none;
  transition: color 0.18s ease, border-color 0.18s ease;
}

a:hover {
  color: var(--ochre-dark);
}

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

figure {
  margin: 0;
}

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

button {
  font: inherit;
  color: inherit;
}

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

/* ============ layout · shell ============ */

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

.header-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px;
  min-height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 20px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  color: var(--ink);
  font-weight: 700;
  font-size: 17px;
  letter-spacing: 0.02em;
  padding: 8px 0;
}

.brand:hover {
  color: var(--ink);
}

.brand-mark {
  width: 26px;
  height: 26px;
  flex: 0 0 26px;
  border-radius: 4px;
  background-color: var(--ink);
  border: 1px solid var(--ink);
  position: relative;
}

.brand-mark::after {
  content: "";
  position: absolute;
  inset: 6px;
  border: 1.5px solid var(--paper);
  border-radius: 1px;
}

.brand-text {
  white-space: nowrap;
}

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

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

.nav-list > li {
  display: flex;
}

.nav-link {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 14px;
  color: var(--ink-soft);
  font-size: 15px;
  border-bottom: 2px solid transparent;
  transition: color 0.18s ease, border-color 0.18s ease;
}

.nav-link:hover {
  color: var(--ink);
  border-bottom-color: var(--rule);
}

.nav-link.is-current {
  color: var(--ochre);
  font-weight: 700;
  border-bottom-color: var(--ochre);
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  padding: 0;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--card);
  cursor: pointer;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 4px;
}

.nav-toggle-bar {
  display: block;
  width: 18px;
  height: 2px;
  background-color: var(--ink);
  border-radius: 1px;
}

.site-main {
  display: block;
}

.inner-main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 28px 24px 72px;
}

.breadcrumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 20px;
}

.breadcrumb a {
  color: var(--ink-soft);
  border-bottom: 1px solid var(--rule);
  padding-bottom: 1px;
}

.breadcrumb a:hover {
  color: var(--ochre);
  border-bottom-color: var(--ochre);
}

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

.breadcrumb-current {
  color: var(--ink);
  font-weight: 600;
}

.page-header {
  max-width: var(--readw);
  margin-bottom: 40px;
  padding-bottom: 24px;
  border-bottom: 1px solid var(--rule);
}

.page-description {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.14em;
  text-transform: uppercase;
  color: var(--moss);
  margin-bottom: 10px;
}

.page-title {
  font-size: 34px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 14px;
}

.page-lead,
.page-intro {
  font-size: 16px;
  color: var(--ink-soft);
  line-height: 1.8;
}

.page-layout {
  display: grid;
  gap: 40px;
}

.sidebar-left .page-layout {
  grid-template-columns: 220px minmax(0, 1fr);
}

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

.section-title {
  font-size: 22px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 12px;
}

.section-lead,
.section-intro {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 24px;
}

.section-more {
  margin-top: 22px;
  font-size: 15px;
}

.text-link {
  color: var(--ochre);
  border-bottom: 1px solid var(--rule);
  padding-bottom: 1px;
}

.text-link:hover {
  color: var(--ochre-dark);
  border-bottom-color: var(--ochre);
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 22px;
  border-radius: var(--radius);
  font-size: 15px;
  font-weight: 600;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color 0.18s ease, border-color 0.18s ease, color 0.18s ease;
}

.btn-primary {
  background-color: var(--ochre);
  border-color: var(--ochre);
  color: #FBF8F1;
}

.btn-primary:hover {
  background-color: var(--ochre-dark);
  border-color: var(--ochre-dark);
  color: #FBF8F1;
}

.btn-ghost {
  background-color: transparent;
  border-color: var(--rule);
  color: var(--ink);
}

.btn-ghost:hover {
  border-color: var(--ink-soft);
  color: var(--ink);
}

.btn-outline {
  background-color: transparent;
  border-color: var(--rule);
  color: var(--ochre);
  white-space: nowrap;
}

.btn-outline:hover {
  border-color: var(--ochre);
  background-color: var(--card);
  color: var(--ochre-dark);
}

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

.field-table {
  font-size: 14px;
  min-width: 560px;
}

.field-table caption,
.field-table-caption,
.table-caption {
  caption-side: top;
  text-align: left;
  padding: 14px 18px 0;
  font-size: 13px;
  color: var(--ink-soft);
}

.field-table th,
.field-table td {
  padding: 12px 18px;
  text-align: left;
  vertical-align: top;
  border-bottom: 1px solid var(--rule-soft);
}

.field-table thead th {
  font-size: 13px;
  color: var(--moss);
  font-weight: 600;
  letter-spacing: 0.06em;
  background-color: #F2EBDD;
  border-bottom: 1px solid var(--rule);
}

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

.field-table tbody tr:last-child th,
.field-table tbody tr:last-child td {
  border-bottom: none;
}

.field-table tbody tr:hover {
  background-color: #F5EFE3;
}

.aside-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--ink);
  padding-bottom: 10px;
  border-bottom: 1px solid var(--rule);
  margin-bottom: 14px;
}

.aside-list {
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.aside-list a {
  display: block;
  padding: 9px 10px;
  font-size: 14px;
  color: var(--ink-soft);
  border-left: 2px solid var(--rule);
  border-radius: 0 4px 4px 0;
}

.aside-list a:hover {
  color: var(--ochre);
  border-left-color: var(--ochre);
  background-color: var(--card);
}

.aside-note {
  margin-top: 18px;
  font-size: 13px;
  line-height: 1.7;
  color: var(--ink-soft);
  padding-top: 14px;
  border-top: 1px dashed var(--rule);
}

.path-list {
  display: flex;
  flex-direction: column;
  gap: 16px;
  counter-reset: path;
}

.path-step,
.path-item {
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr);
  gap: 14px;
  align-items: start;
}

.path-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 30px;
  height: 30px;
  border-radius: 50%;
  border: 1px solid var(--rule);
  background-color: var(--card);
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--moss);
}

.path-name,
.path-title {
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 6px;
}

.path-text {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.8;
}

.path-text .text-link {
  margin-left: 4px;
}

.path-body {
  min-width: 0;
}

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

.site-footer {
  background-color: #EFE7D8;
  border-top: 1px solid var(--rule);
}

.footer-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 48px 24px 32px;
  display: grid;
  grid-template-columns: 1.4fr 1fr 1.4fr 1fr;
  gap: 32px;
}

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

.footer-title {
  font-size: 14px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 14px;
  letter-spacing: 0.04em;
}

.footer-text {
  font-size: 14px;
  line-height: 1.8;
  color: var(--ink-soft);
}

.footer-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.footer-list a {
  font-size: 14px;
  color: var(--ink-soft);
}

.footer-list a:hover {
  color: var(--ochre);
}

.footer-bottom {
  border-top: 1px solid var(--rule);
  background-color: #E9E0CF;
}

.footer-copy {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 16px 24px;
  font-size: 13px;
  color: var(--ink-soft);
}

/* ============ pages · index ============ */

.home-main {
  display: block;
}

.hero {
  border-bottom: 1px solid var(--rule);
  background-color: #F2EBDD;
}

.hero-inner {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 56px 24px 40px;
  display: grid;
  grid-template-columns: minmax(0, 1.35fr) minmax(0, 1fr);
  gap: 48px;
  align-items: start;
}

.hero-kicker {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  text-transform: uppercase;
  color: var(--moss);
  margin-bottom: 14px;
}

.hero-title {
  font-size: 40px;
  line-height: 1.28;
  color: var(--ink);
  margin-bottom: 18px;
}

.hero-lead {
  font-size: 17px;
  line-height: 1.85;
  color: var(--ink-soft);
  max-width: 34em;
  margin-bottom: 22px;
}

.hero-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
}

.hero-meta li {
  font-size: 13px;
  color: var(--ink-soft);
  padding: 5px 12px;
  border: 1px solid var(--rule);
  border-radius: 999px;
  background-color: var(--card);
}

.hero-paths {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--card);
  padding: 22px;
  box-shadow: var(--shadow);
}

.hero-paths-title {
  font-size: 15px;
  font-weight: 700;
  color: var(--ink);
  padding-bottom: 12px;
  margin-bottom: 16px;
  border-bottom: 1px solid var(--rule-soft);
}

.path-button {
  display: block;
  padding: 14px 16px;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--paper);
  margin-bottom: 10px;
  transition: transform 0.18s ease, border-color 0.18s ease, background-color 0.18s ease;
}

.path-button:last-child {
  margin-bottom: 0;
}

.path-button:hover {
  transform: translateY(-2px);
  border-color: var(--ochre);
  background-color: #FBF6EC;
}

.path-button-label {
  display: block;
  font-size: 16px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 3px;
}

.path-button-note {
  display: block;
  font-size: 13px;
  color: var(--ink-soft);
  line-height: 1.7;
}

.path-button-primary {
  background-color: var(--ochre);
  border-color: var(--ochre);
}

.path-button-primary .path-button-label,
.path-button-primary .path-button-note {
  color: #FBF8F1;
}

.path-button-primary:hover {
  background-color: var(--ochre-dark);
  border-color: var(--ochre-dark);
}

.hero-figure {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 0 24px 48px;
}

.hero-figure img {
  width: 100%;
  height: 320px;
  object-fit: cover;
  border-radius: var(--radius);
  border: 1px solid var(--rule);
}

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

.channels,
.topics,
.catalog-fields,
.guide-points,
.boundaries {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 56px 24px;
  border-bottom: 1px solid var(--rule-soft);
}

.boundaries {
  border-bottom: none;
}

.section-head {
  max-width: var(--readw);
  margin-bottom: 32px;
}

.section-index {
  font-family: var(--font-mono);
  font-size: 12px;
  letter-spacing: 0.16em;
  color: var(--moss);
  margin-bottom: 8px;
}

.section-desc {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.8;
}

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

.channel-card {
  display: flex;
  flex-direction: column;
  background-color: var(--card);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.18s ease, border-color 0.18s ease;
}

.channel-card:hover {
  transform: translateY(-3px);
  border-color: var(--ochre);
}

.channel-figure {
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background-color: #E9E0CF;
}

.channel-figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.channel-name {
  font-size: 17px;
  font-weight: 700;
  padding: 16px 18px 8px;
}

.channel-scope {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.75;
  padding: 0 18px 14px;
  flex: 1 1 auto;
}

.channel-link {
  display: inline-block;
  margin: 0 18px 18px;
  padding-top: 12px;
  font-size: 14px;
  font-weight: 600;
  color: var(--ochre);
  border-top: 1px solid var(--rule-soft);
}

.channel-link:hover {
  color: var(--ochre-dark);
}

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

.topic-card {
  display: flex;
  flex-direction: column;
  background-color: var(--card);
  border: 1px solid var(--rule);
  border-left: 3px solid var(--moss);
  border-radius: var(--radius);
  padding: 22px;
  transition: transform 0.18s ease, border-color 0.18s ease;
}

.topic-card:hover {
  transform: translateY(-3px);
  border-color: var(--ochre);
  border-left-color: var(--ochre);
}

.topic-name {
  font-size: 18px;
  font-weight: 700;
  margin-bottom: 10px;
}

.topic-scope {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.8;
  margin-bottom: 12px;
}

.topic-channel {
  font-size: 13px;
  color: var(--moss);
  margin-bottom: 16px;
}

.topic-link {
  margin-top: auto;
  font-size: 14px;
  font-weight: 600;
  color: var(--ochre);
  padding-top: 12px;
  border-top: 1px solid var(--rule-soft);
}

.topic-link:hover {
  color: var(--ochre-dark);
}

.point-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 22px;
}

.point-item {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 14px;
  align-items: start;
  background-color: var(--card);
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  padding: 20px;
}

.point-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  background-color: var(--ink);
  color: var(--paper);
  font-family: var(--font-mono);
  font-size: 14px;
}

.point-body {
  min-width: 0;
}

.point-title {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 6px;
}

.point-body p {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.8;
}

.boundary-block {
  max-width: var(--readw);
  padding: 24px;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--ochre);
  border-radius: var(--radius);
  background-color: var(--card);
}

.boundary-text {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.85;
  margin-bottom: 14px;
}

.boundary-text:last-of-type {
  margin-bottom: 18px;
}

.boundary-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 20px;
  font-size: 15px;
}

/* ============ pages · channel ============ */

.channel-content {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 52px;
}

.channel-section {
  min-width: 0;
}

.channel-item {
  display: grid;
  grid-template-columns: 180px minmax(0, 1fr) auto;
  gap: 22px;
  align-items: center;
  padding: 20px 0;
  border-bottom: 1px solid var(--rule-soft);
}

.channel-item:first-of-type {
  border-top: 1px solid var(--rule-soft);
}

.channel-item .channel-figure {
  aspect-ratio: 16 / 10;
  border-radius: var(--radius);
  border: 1px solid var(--rule);
}

.channel-body {
  min-width: 0;
}

.channel-body .channel-name {
  padding: 0;
  margin-bottom: 8px;
}

.channel-body .channel-scope {
  padding: 0;
  margin-bottom: 8px;
}

.channel-meta {
  font-size: 13px;
  color: var(--moss);
}

.channel-enter {
  flex: 0 0 auto;
}

.diff-list {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.diff-item {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--card);
  padding: 20px;
}

.diff-col {
  display: inline-flex;
  flex-direction: column;
  vertical-align: top;
  width: calc(50% - 12px);
  padding-right: 16px;
}

.diff-col + .diff-col {
  padding-left: 16px;
  padding-right: 0;
  border-left: 1px solid var(--rule-soft);
}

.diff-name {
  font-size: 15px;
  font-weight: 700;
  color: var(--ink);
  margin-bottom: 6px;
}

.diff-text {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.8;
}

.diff-note {
  margin-top: 16px;
  padding-top: 14px;
  border-top: 1px dashed var(--rule);
  font-size: 14px;
  color: var(--moss);
  line-height: 1.8;
}

/* ============ pages · topic ============ */

.topic-content {
  min-width: 0;
  display: flex;
  flex-direction: column;
  gap: 52px;
}

.section {
  min-width: 0;
}

.topic-list {
  display: flex;
  flex-direction: column;
  gap: 22px;
}

.topic-list .topic-card {
  display: grid;
  grid-template-columns: 220px minmax(0, 1fr);
  gap: 24px;
  padding: 20px;
  border-left: 3px solid var(--moss);
}

.topic-media {
  aspect-ratio: 16 / 10;
  border-radius: var(--radius);
  overflow: hidden;
  border: 1px solid var(--rule);
  background-color: #E9E0CF;
}

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

.topic-body {
  min-width: 0;
  display: flex;
  flex-direction: column;
}

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

.topic-index {
  font-family: var(--font-mono);
  font-size: 12px;
  color: var(--moss);
  letter-spacing: 0.1em;
}

.topic-meta {
  font-size: 13px;
  color: var(--moss);
  margin-bottom: 16px;
}

.topic-body .topic-link {
  margin-top: auto;
}

.section-note {
  margin-top: 20px;
  font-size: 14px;
  color: var(--ink-soft);
}

/* ============ pages · catalog ============ */

.catalog-figure {
  margin-bottom: 44px;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--card);
}

.catalog-figure img {
  width: 100%;
  height: 260px;
  object-fit: cover;
}

.catalog-figure-caption {
  padding: 12px 18px;
  font-size: 13px;
  color: var(--ink-soft);
  border-top: 1px solid var(--rule-soft);
}

.catalog-fields,
.field-limits,
.back-path {
  max-width: var(--readw);
  margin-bottom: 52px;
}

.catalog-fields .field-table {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--card);
  overflow: hidden;
}

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

.limit-item {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--card);
  padding: 20px;
}

.limit-title {
  font-size: 16px;
  font-weight: 700;
  margin-bottom: 8px;
}

.limit-text {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.8;
}

/* ============ pages · guide ============ */

.guide-order,
.guide-faq,
.guide-feedback {
  max-width: var(--readw);
  margin-bottom: 52px;
}

.order-list {
  display: flex;
  flex-direction: column;
  gap: 18px;
}

.order-item {
  display: grid;
  grid-template-columns: 40px minmax(0, 1fr);
  gap: 16px;
  align-items: start;
  padding: 18px 0;
  border-bottom: 1px solid var(--rule-soft);
}

.order-item:first-child {
  border-top: 1px solid var(--rule-soft);
}

.order-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 34px;
  height: 34px;
  border-radius: 50%;
  border: 1px solid var(--ochre);
  color: var(--ochre);
  font-family: var(--font-mono);
  font-size: 14px;
}

.order-body {
  min-width: 0;
}

.order-title {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 6px;
}

.order-text {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.85;
}

.guide-figure {
  margin-top: 28px;
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--card);
}

.guide-figure img {
  width: 100%;
  height: 240px;
  object-fit: cover;
}

.guide-figure figcaption {
  padding: 12px 18px;
  font-size: 13px;
  color: var(--ink-soft);
  border-top: 1px solid var(--rule-soft);
}

.faq-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.faq-item {
  border: 1px solid var(--rule);
  border-radius: var(--radius);
  background-color: var(--card);
  overflow: hidden;
}

.faq-question {
  display: block;
  padding: 16px 20px;
  font-size: 16px;
  font-weight: 600;
  color: var(--ink);
  cursor: pointer;
  list-style: none;
  position: relative;
  padding-right: 52px;
}

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

.faq-question::after {
  content: "+";
  position: absolute;
  right: 20px;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  font-size: 20px;
  color: var(--ochre);
  line-height: 1;
}

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

.faq-item[open] .faq-question {
  color: var(--ochre);
}

.faq-answer {
  padding: 0 20px 18px;
  border-top: 1px solid var(--rule-soft);
  padding-top: 14px;
}

.faq-answer p {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.85;
}

.feedback-block {
  border: 1px solid var(--rule);
  border-left: 3px solid var(--moss);
  border-radius: var(--radius);
  background-color: var(--card);
  padding: 24px;
}

.feedback-title {
  font-size: 17px;
  font-weight: 700;
  margin-bottom: 14px;
}

.feedback-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
  margin-bottom: 18px;
}

.feedback-item {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.8;
  padding-left: 20px;
  position: relative;
}

.feedback-item::before {
  content: "";
  position: absolute;
  left: 2px;
  top: 0.72em;
  width: 7px;
  height: 7px;
  border-radius: 50%;
  background-color: var(--moss);
}

.feedback-note {
  font-size: 15px;
  color: var(--ink-soft);
  padding-top: 16px;
  border-top: 1px dashed var(--rule);
}

.feedback-note a {
  margin-right: 18px;
}

/* ============ pages · 404 ============ */

.error-main {
  max-width: var(--maxw);
  margin: 0 auto;
  padding: 72px 24px 96px;
  display: flex;
  justify-content: center;
}

.error-panel {
  max-width: 560px;
  width: 100%;
  text-align: left;
  border: 1px solid var(--rule);
  border-left: 3px solid var(--ochre);
  border-radius: var(--radius);
  background-color: var(--card);
  padding: 40px 32px;
}

.error-code {
  font-family: var(--font-mono);
  font-size: 13px;
  letter-spacing: 0.18em;
  color: var(--moss);
  margin-bottom: 12px;
}

.error-title {
  font-size: 30px;
  margin-bottom: 16px;
}

.error-text {
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.85;
  margin-bottom: 12px;
}

.error-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 14px;
  margin-top: 24px;
}

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

@media (max-width: 900px) {
  .nav-toggle {
    display: inline-flex;
  }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--paper);
    border-bottom: 1px solid var(--rule);
    padding: 8px 16px 16px;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
  }

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

  .nav-list > li {
    display: block;
  }

  .nav-link {
    min-height: 48px;
    padding: 0 6px;
    border-bottom: 1px solid var(--rule-soft);
    border-left: 2px solid transparent;
  }

  .nav-link.is-current {
    border-bottom-color: var(--rule-soft);
    border-left-color: var(--ochre);
    padding-left: 12px;
  }

  .hero-inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 32px;
    padding: 40px 20px 32px;
  }

  .hero-title {
    font-size: 30px;
  }

  .hero-figure {
    padding: 0 20px 36px;
  }

  .hero-figure img {
    height: 240px;
  }

  .channels,
  .topics,
  .catalog-fields,
  .guide-points,
  .boundaries {
    padding: 40px 20px;
  }

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

  .inner-main {
    padding: 22px 20px 56px;
  }

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

  .sidebar-left .page-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 32px;
  }

  .sidebar-left .channel-nav,
  .sidebar-left .topic-nav {
    order: 2;
  }

  .sidebar-left .channel-content,
  .sidebar-left .topic-content {
    order: 1;
  }

  .footer-inner {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 28px;
    padding: 40px 20px 28px;
  }

  .footer-copy {
    padding: 14px 20px;
  }
}

@media (max-width: 600px) {
  .header-inner {
    padding: 0 16px;
    min-height: 58px;
  }

  .brand {
    font-size: 16px;
  }

  .hero-title {
    font-size: 26px;
  }

  .hero-lead {
    font-size: 16px;
  }

  .hero-figure img {
    height: 190px;
  }

  .channel-grid,
  .topic-grid,
  .point-list,
  .limit-grid {
    grid-template-columns: minmax(0, 1fr);
  }

  .channel-item {
    grid-template-columns: minmax(0, 1fr);
    gap: 14px;
  }

  .channel-item .channel-figure {
    aspect-ratio: 16 / 9;
  }

  .channel-enter {
    justify-self: start;
  }

  .diff-col {
    display: block;
    width: 100%;
    padding-right: 0;
  }

  .diff-col + .diff-col {
    padding-left: 0;
    margin-top: 14px;
    padding-top: 14px;
    border-left: none;
    border-top: 1px solid var(--rule-soft);
  }

  .topic-list .topic-card {
    grid-template-columns: minmax(0, 1fr);
    gap: 16px;
  }

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

  .catalog-figure img,
  .guide-figure img {
    height: 180px;
  }

  .error-panel {
    padding: 28px 20px;
  }

  .error-title {
    font-size: 24px;
  }

  .footer-inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 24px;
  }
}