:root {
  --color-bg: #FBF9F5;
  --color-primary: #1F3A2E;
  --color-accent: #D98CA6;
  --color-muted: #6B7A6F;
  --color-line: #E3DED4;
  --color-surface: #FFFFFF;
  --font-stack: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", "Noto Sans CJK SC", sans-serif;
  --font-mono: "SF Mono", "Menlo", "Consolas", "Courier New", monospace;
  --container: 1120px;
  --radius: 6px;
  --radius-sm: 4px;
  --shadow-card: 0 1px 3px rgba(31, 58, 46, 0.06);
}

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

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

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

body {
  margin: 0;
  font-family: var(--font-stack);
  font-size: 16px;
  line-height: 1.8;
  color: var(--color-primary);
  background-color: var(--color-bg);
  -webkit-font-smoothing: antialiased;
}

h1, h2, h3, h4 {
  margin: 0 0 0.6em;
  font-weight: 600;
  line-height: 1.35;
  color: var(--color-primary);
}

h1 { font-size: 30px; }
h2 { font-size: 22px; }
h3 { font-size: 18px; }

p {
  margin: 0 0 1em;
  color: var(--color-primary);
}

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

a {
  color: var(--color-primary);
  text-decoration: none;
  border-bottom: 1px solid transparent;
  transition: color 0.15s ease, border-color 0.15s ease;
}

a:hover,
a:focus-visible {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

a:focus-visible {
  outline: 2px solid var(--color-accent);
  outline-offset: 2px;
}

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

figure {
  margin: 0;
}

ul, ol {
  margin: 0 0 1em;
  padding-left: 1.4em;
}

li {
  margin-bottom: 0.35em;
}

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

button {
  font-family: inherit;
  font-size: inherit;
  cursor: pointer;
}

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

/* ============================================================
   layout — shell
   ============================================================ */

.site-header {
  position: sticky;
  top: 0;
  z-index: 100;
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-line);
}

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

.brand {
  font-size: 20px;
  font-weight: 600;
  color: var(--color-primary);
  border-bottom: none;
  letter-spacing: 0.02em;
  white-space: nowrap;
  flex-shrink: 0;
}

.brand:hover,
.brand:focus-visible {
  color: var(--color-accent);
  border-bottom-color: transparent;
}

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

.nav-list {
  display: flex;
  align-items: center;
  gap: 4px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.nav-list li {
  margin: 0;
}

.nav-list a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 14px;
  font-size: 15px;
  color: var(--color-primary);
  border-bottom: 2px solid transparent;
  border-radius: var(--radius-sm);
}

.nav-list a:hover,
.nav-list a:focus-visible {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.nav-list a.is-current {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
  font-weight: 600;
}

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

.nav-toggle-bar {
  display: block;
  width: 20px;
  height: 2px;
  background-color: var(--color-primary);
  border-radius: 1px;
}

.site-main {
  display: block;
}

.inner-main {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px 64px;
}

.home-main {
  display: block;
}

.site-footer {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-line);
  margin-top: 0;
}

.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 48px 24px 32px;
}

.footer-groups {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 32px;
  padding-bottom: 32px;
  border-bottom: 1px solid var(--color-line);
}

.footer-group-title {
  font-size: 15px;
  font-weight: 600;
  margin: 0 0 12px;
  color: var(--color-primary);
}

.footer-group ul {
  list-style: none;
  margin: 0;
  padding: 0;
}

.footer-group li {
  margin-bottom: 8px;
}

.footer-group a {
  font-size: 14px;
  color: var(--color-muted);
  border-bottom: 1px solid transparent;
}

.footer-group a:hover,
.footer-group a:focus-visible {
  color: var(--color-accent);
  border-bottom-color: var(--color-accent);
}

.footer-bottom {
  padding-top: 24px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 32px;
  align-items: baseline;
}

.footer-brand {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-primary);
  margin: 0;
}

.footer-note {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
}

.footer-copy {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
}

/* ============================================================
   layout — inner page shared
   ============================================================ */

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 24px 0 0;
  font-size: 14px;
  color: var(--color-muted);
}

.breadcrumb a {
  color: var(--color-muted);
  border-bottom: 1px solid transparent;
}

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

.breadcrumb-sep {
  color: var(--color-line);
  user-select: none;
}

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

.page-header {
  padding: 24px 0 32px;
  border-bottom: 1px solid var(--color-line);
  margin-bottom: 40px;
}

.page-title {
  font-size: 30px;
  font-weight: 600;
  line-height: 1.3;
  margin: 0 0 12px;
  color: var(--color-primary);
}

.page-description {
  font-size: 16px;
  color: var(--color-muted);
  max-width: 760px;
  margin: 0;
  line-height: 1.8;
}

.page-description a {
  color: var(--color-accent);
  border-bottom: 1px solid var(--color-accent);
}

.page-description a:hover,
.page-description a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.section-title {
  font-size: 22px;
  font-weight: 600;
  margin: 0 0 12px;
  color: var(--color-primary);
}

.section-lead,
.section-note,
.section-desc {
  font-size: 15px;
  color: var(--color-muted);
  max-width: 760px;
  margin: 0 0 24px;
  line-height: 1.8;
}

.section-lead a,
.section-note a,
.section-desc a {
  color: var(--color-accent);
  border-bottom: 1px solid var(--color-accent);
}

.section-lead a:hover,
.section-note a:hover,
.section-desc a:hover,
.section-lead a:focus-visible,
.section-note a:focus-visible,
.section-desc a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ============================================================
   components — buttons
   ============================================================ */

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 22px;
  font-size: 15px;
  font-weight: 600;
  border-radius: var(--radius);
  border: 1px solid transparent;
  transition: background-color 0.15s ease, color 0.15s ease, border-color 0.15s ease;
  text-align: center;
  white-space: nowrap;
}

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

.btn-primary:hover,
.btn-primary:focus-visible {
  background-color: var(--color-accent);
  border-color: var(--color-accent);
  color: #FFFFFF;
}

.btn-outline {
  background-color: rgba(255, 255, 255, 0.92);
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.btn-outline:hover,
.btn-outline:focus-visible {
  background-color: var(--color-primary);
  color: #FFFFFF;
}

.btn-ghost {
  background-color: transparent;
  color: var(--color-primary);
  border-color: var(--color-line);
}

.btn-ghost:hover,
.btn-ghost:focus-visible {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   components — section head (homepage)
   ============================================================ */

.section-head {
  margin-bottom: 32px;
}

.section-head h2 {
  font-size: 22px;
  font-weight: 600;
  margin: 0 0 8px;
  color: var(--color-primary);
}

.section-head p {
  font-size: 15px;
  color: var(--color-muted);
  max-width: 760px;
  margin: 0;
}

.section-more {
  margin: 28px 0 0;
  font-size: 15px;
}

.section-more a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.section-more a:hover,
.section-more a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ============================================================
   components — figures & images
   ============================================================ */

figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

figcaption {
  font-size: 13px;
  color: var(--color-muted);
  margin-top: 8px;
  line-height: 1.6;
}

/* ============================================================
   components — field table (shared)
   ============================================================ */

.field-table {
  width: 100%;
  border-collapse: collapse;
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  overflow: hidden;
  font-size: 15px;
}

.field-table-caption {
  caption-side: top;
  text-align: left;
  font-size: 14px;
  color: var(--color-muted);
  padding: 0 0 10px;
}

.field-table thead th {
  background-color: #F4F1EA;
  color: var(--color-primary);
  font-weight: 600;
  font-size: 14px;
  text-align: left;
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-line);
  white-space: nowrap;
}

.field-table tbody th {
  text-align: left;
  font-weight: 600;
  font-size: 14px;
  color: var(--color-primary);
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-line);
  background-color: #FDFCFA;
  white-space: nowrap;
  vertical-align: top;
}

.field-table tbody td {
  padding: 12px 16px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-primary);
  vertical-align: top;
  line-height: 1.7;
}

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

.field-table tbody td:last-child {
  font-family: var(--font-mono);
  font-size: 13px;
  color: var(--color-muted);
}

/* ============================================================
   components — boundary lists (shared)
   ============================================================ */

.boundary-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.boundary-list li {
  position: relative;
  padding-left: 20px;
  margin-bottom: 10px;
  font-size: 15px;
  line-height: 1.75;
  color: var(--color-primary);
}

.boundary-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.7em;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--color-accent);
}

.boundary-exclude .boundary-list li::before {
  background-color: var(--color-line);
}

/* ============================================================
   pages — index.html
   ============================================================ */

/* hero focus */
.hero-focus {
  position: relative;
  overflow: hidden;
  background-color: var(--color-primary);
}

.hero-media {
  position: relative;
  width: 100%;
  height: 480px;
  margin: 0;
}

.hero-media img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 0;
}

.hero-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: flex-start;
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
  left: 0;
  right: 0;
  background-color: rgba(31, 58, 46, 0.55);
}

.hero-title {
  font-size: 34px;
  font-weight: 600;
  line-height: 1.3;
  color: #FFFFFF;
  margin: 0 0 16px;
  max-width: 640px;
}

.hero-lead {
  font-size: 16px;
  color: rgba(255, 255, 255, 0.9);
  max-width: 560px;
  margin: 0 0 28px;
  line-height: 1.8;
}

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

/* channel overview */
.channel-overview,
.collection-preview,
.field-summary,
.browse-steps,
.page-index {
  max-width: var(--container);
  margin: 0 auto;
  padding: 64px 24px;
}

.channel-overview {
  padding-top: 72px;
}

.channel-rows {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--color-line);
}

.channel-row {
  display: grid;
  grid-template-columns: 200px minmax(0, 1.2fr) minmax(0, 1fr) minmax(0, 1fr);
  gap: 20px;
  align-items: start;
  padding: 20px 0;
  border-bottom: 1px solid var(--color-line);
}

.channel-name {
  font-size: 17px;
  font-weight: 600;
  margin: 0;
  color: var(--color-primary);
  display: flex;
  align-items: baseline;
  gap: 8px;
  flex-wrap: wrap;
}

.channel-tag {
  display: inline-block;
  width: 10px;
  height: 10px;
  border-radius: 50%;
  background-color: var(--color-accent);
  flex-shrink: 0;
}

.channel-row .channel-scope,
.channel-row .channel-field,
.channel-row .channel-scene {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.7;
}

.channel-row .channel-scope {
  color: var(--color-primary);
}

/* collection preview grid */
.collection-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
}

.collection-card {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  overflow: hidden;
  display: flex;
  flex-direction: column;
  transition: box-shadow 0.15s ease, border-color 0.15s ease;
}

.collection-card:hover {
  border-color: var(--color-accent);
  box-shadow: var(--shadow-card);
}

.collection-cover {
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  margin: 0;
  background-color: #F4F1EA;
}

.collection-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: 0;
}

.collection-card .collection-name {
  font-size: 18px;
  font-weight: 600;
  margin: 20px 20px 8px;
  color: var(--color-primary);
}

.collection-card .collection-range,
.collection-card .collection-field,
.collection-card .collection-boundary {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0 20px 8px;
  line-height: 1.7;
}

.collection-card .collection-boundary {
  margin-bottom: 20px;
  padding-top: 8px;
  border-top: 1px dashed var(--color-line);
}

/* field summary section */
.field-summary .field-table {
  margin-top: 8px;
}

/* browse steps */
.step-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--color-line);
}

.step-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  padding: 20px 0;
  border-bottom: 1px solid var(--color-line);
}

.step-no {
  flex-shrink: 0;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-primary);
  color: #FFFFFF;
  font-size: 16px;
  font-weight: 600;
  border-radius: 50%;
  font-family: var(--font-mono);
}

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

.step-name {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 6px;
  color: var(--color-primary);
}

.step-body p {
  font-size: 15px;
  color: var(--color-muted);
  margin: 0 0 8px;
  line-height: 1.75;
}

.step-body a {
  font-size: 14px;
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.step-body a:hover,
.step-body a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* page index */
.page-index {
  background-color: var(--color-surface);
  border-top: 1px solid var(--color-line);
  border-bottom: 1px solid var(--color-line);
}

.index-columns {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 24px;
}

.index-col {
  padding: 20px;
  background-color: var(--color-bg);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
}

.index-col-title {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 8px;
  color: var(--color-primary);
}

.index-col p {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0 0 12px;
  line-height: 1.7;
}

.index-col a {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-accent);
  border-bottom: 1px solid var(--color-accent);
}

.index-col a:hover,
.index-col a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ============================================================
   pages — theme-channels.html
   ============================================================ */

.channel-list-section,
.field-focus-section,
.channel-boundary-section {
  margin-bottom: 56px;
}

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

.channel-list-section .channel-row {
  display: grid;
  grid-template-columns: 200px minmax(0, 1fr);
  gap: 24px;
  align-items: start;
  padding: 24px 0;
  border-bottom: 1px solid var(--color-line);
}

.channel-figure {
  width: 200px;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  margin: 0;
  background-color: #F4F1EA;
  border-radius: var(--radius-sm);
}

.channel-figure img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  border-radius: var(--radius-sm);
}

.channel-figure figcaption {
  font-size: 13px;
  margin-top: 8px;
}

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

.channel-body .channel-name {
  font-size: 18px;
  font-weight: 600;
  margin: 0 0 10px;
  color: var(--color-primary);
}

.channel-body .channel-scope,
.channel-body .channel-field,
.channel-body .channel-usage {
  font-size: 15px;
  color: var(--color-muted);
  margin: 0 0 6px;
  line-height: 1.75;
}

.channel-body .channel-scope {
  color: var(--color-primary);
}

.field-focus-groups {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px;
}

.field-focus-group {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 20px;
}

.field-focus-group h3 {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 8px;
  color: var(--color-primary);
}

.field-focus-group p {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.75;
}

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

.boundary-block {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 24px;
}

.boundary-block h3 {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-primary);
}

.boundary-tail {
  margin-top: 24px;
  font-size: 15px;
}

.boundary-tail a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.boundary-tail a:hover,
.boundary-tail a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ============================================================
   pages — collection-index.html
   ============================================================ */

.collection-list-section,
.collection-scope,
.collection-boundary,
.collection-guide {
  margin-bottom: 56px;
}

.collection-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 24px;
}

.collection-item {
  margin: 0;
}

.collection-item .collection-card {
  display: grid;
  grid-template-columns: 180px minmax(0, 1fr);
  gap: 0;
  height: 100%;
}

.collection-item .collection-cover {
  width: 180px;
  height: 100%;
  min-height: 180px;
  aspect-ratio: auto;
  border-radius: 0;
}

.collection-item .collection-cover img {
  border-radius: 0;
}

.collection-body {
  padding: 20px;
  min-width: 0;
}

.collection-body .collection-name {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 12px;
  color: var(--color-primary);
}

.collection-meta {
  margin: 0;
  font-size: 14px;
}

.collection-meta dt {
  font-weight: 600;
  color: var(--color-primary);
  margin-top: 10px;
  font-size: 14px;
}

.collection-meta dt:first-child {
  margin-top: 0;
}

.collection-meta dd {
  margin: 2px 0 0;
  color: var(--color-muted);
  line-height: 1.7;
}

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

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

.scope-name {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 8px;
  color: var(--color-primary);
}

.scope-item p {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.75;
}

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

.boundary-column {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 24px;
}

.boundary-title {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 16px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-primary);
}

.collection-guide {
  padding: 24px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
}

.collection-guide h2 {
  font-size: 20px;
  font-weight: 600;
  margin: 0 0 12px;
  color: var(--color-primary);
}

.collection-guide p {
  font-size: 15px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.8;
  max-width: 760px;
}

.collection-guide a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.collection-guide a:hover,
.collection-guide a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ============================================================
   pages — field-guide.html
   ============================================================ */

.field-table-section,
.field-usage-section,
.field-boundary-section {
  margin-bottom: 56px;
}

.field-figure {
  width: 100%;
  max-width: 760px;
  margin: 0 0 24px;
  background-color: #F4F1EA;
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  overflow: hidden;
}

.field-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: 0;
}

.field-figure figcaption {
  padding: 12px 16px;
  font-size: 13px;
  margin: 0;
}

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

.usage-column {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 24px;
}

.subsection-title {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 14px;
  padding-bottom: 10px;
  border-bottom: 1px solid var(--color-line);
  color: var(--color-primary);
}

.usage-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.usage-list li {
  position: relative;
  padding-left: 18px;
  margin-bottom: 10px;
  font-size: 15px;
  color: var(--color-muted);
  line-height: 1.75;
}

.usage-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 0.7em;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--color-accent);
}

.field-boundary-section .boundary-list {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 20px;
  margin-bottom: 24px;
}

.boundary-item {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  padding: 20px;
  margin: 0;
}

.boundary-item .boundary-title {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 8px;
  padding-bottom: 0;
  border-bottom: none;
  color: var(--color-primary);
}

.boundary-item p {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.75;
}

/* ============================================================
   pages — browse-path.html
   ============================================================ */

.path-steps,
.path-faq,
.feedback-entry {
  margin-bottom: 56px;
}

.path-steps .step-list {
  border-top: 1px solid var(--color-line);
  margin-bottom: 32px;
}

.path-steps .step-item {
  display: flex;
  gap: 20px;
  align-items: flex-start;
  padding: 24px 0;
  border-bottom: 1px solid var(--color-line);
}

.step-index {
  flex-shrink: 0;
  width: 44px;
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--color-accent);
  color: #FFFFFF;
  font-size: 17px;
  font-weight: 600;
  border-radius: 50%;
  font-family: var(--font-mono);
}

.path-steps .step-name {
  font-size: 18px;
  font-weight: 600;
  margin: 0 0 6px;
  color: var(--color-primary);
}

.step-text {
  font-size: 15px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.75;
}

.step-text a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.step-text a:hover,
.step-text a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

.path-figure {
  width: 100%;
  max-width: 760px;
  margin: 0;
  background-color: #F4F1EA;
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  overflow: hidden;
}

.path-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
  border-radius: 0;
}

.path-figure figcaption {
  padding: 12px 16px;
  font-size: 13px;
  margin: 0;
}

/* FAQ */
.faq-item {
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  margin-bottom: 12px;
  overflow: hidden;
}

.faq-question {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 16px 20px;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-primary);
  cursor: pointer;
  min-height: 44px;
  list-style: none;
  transition: color 0.15s ease;
}

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

.faq-question::after {
  content: "+";
  flex-shrink: 0;
  font-size: 20px;
  font-weight: 400;
  color: var(--color-accent);
  line-height: 1;
  transition: transform 0.15s ease;
}

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

.faq-question:hover {
  color: var(--color-accent);
}

.faq-answer {
  padding: 0 20px 16px;
  border-top: 1px solid var(--color-line);
  padding-top: 14px;
}

.faq-answer p {
  font-size: 15px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.8;
}

.faq-answer a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.faq-answer a:hover,
.faq-answer a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

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

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

.feedback-card-title {
  font-size: 16px;
  font-weight: 600;
  margin: 0 0 8px;
  color: var(--color-primary);
}

.feedback-card p {
  font-size: 14px;
  color: var(--color-muted);
  margin: 0;
  line-height: 1.75;
}

.feedback-more {
  margin: 24px 0 0;
  font-size: 15px;
}

.feedback-more a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
  margin-right: 20px;
}

.feedback-more a:hover,
.feedback-more a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* print */
.print-action {
  margin-bottom: 56px;
}

.print-button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 22px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-primary);
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  transition: border-color 0.15s ease, color 0.15s ease;
}

.print-button:hover,
.print-button:focus-visible {
  border-color: var(--color-accent);
  color: var(--color-accent);
}

/* ============================================================
   pages — 404.html
   ============================================================ */

.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 80px 24px;
  min-height: 60vh;
}

.container {
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
}

.error-inner {
  max-width: 640px;
  margin: 0 auto;
  text-align: center;
}

.error-code {
  font-family: var(--font-mono);
  font-size: 64px;
  font-weight: 600;
  color: var(--color-accent);
  margin: 0 0 8px;
  line-height: 1;
}

.error-title {
  font-size: 28px;
  font-weight: 600;
  margin: 0 0 16px;
  color: var(--color-primary);
}

.error-text {
  font-size: 16px;
  color: var(--color-muted);
  margin: 0 0 28px;
  line-height: 1.8;
}

.error-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
  justify-content: center;
  margin-bottom: 40px;
}

.error-hint {
  padding: 24px;
  background-color: var(--color-surface);
  border: 1px solid var(--color-line);
  border-radius: var(--radius);
  text-align: left;
}

.error-hint-title {
  font-size: 17px;
  font-weight: 600;
  margin: 0 0 12px;
  color: var(--color-primary);
}

.error-hint-list {
  list-style: none;
  margin: 0;
  padding: 0;
}

.error-hint-list li {
  margin-bottom: 8px;
  font-size: 15px;
}

.error-hint-list a {
  color: var(--color-accent);
  font-weight: 600;
  border-bottom: 1px solid var(--color-accent);
}

.error-hint-list a:hover,
.error-hint-list a:focus-visible {
  color: var(--color-primary);
  border-bottom-color: var(--color-primary);
}

/* ============================================================
   responsive — 960px
   ============================================================ */

@media (max-width: 960px) {

  .header-inner {
    padding: 0 16px;
    min-height: 60px;
    gap: 16px;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    top: 100%;
    left: 0;
    right: 0;
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-line);
    padding: 8px 16px 16px;
    box-shadow: 0 4px 12px rgba(31, 58, 46, 0.08);
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
  }

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

  .nav-list a {
    width: 100%;
    padding: 0 12px;
    border-bottom: 1px solid var(--color-line);
    border-radius: 0;
    justify-content: flex-start;
  }

  .nav-list a.is-current {
    border-bottom-color: var(--color-line);
    border-left: 3px solid var(--color-accent);
    padding-left: 9px;
  }

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

  .footer-inner {
    padding: 40px 16px 28px;
  }

  .inner-main {
    padding: 0 16px 48px;
  }

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

  .hero-media {
    height: 420px;
  }

  .hero-overlay {
    padding: 0 16px;
  }

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

  .channel-overview,
  .collection-preview,
  .field-summary,
  .browse-steps,
  .page-index {
    padding: 48px 16px;
  }

  .channel-row {
    grid-template-columns: 160px minmax(0, 1fr);
    gap: 16px;
  }

  .channel-row .channel-field,
  .channel-row .channel-scene {
    grid-column: 2;
  }

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

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

  .collection-list {
    grid-template-columns: 1fr;
  }

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

  .field-focus-groups {
    grid-template-columns: 1fr;
  }

  .usage-columns {
    grid-template-columns: 1fr;
  }

  .field-boundary-section .boundary-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

/* ============================================================
   responsive — 640px
   ============================================================ */

@media (max-width: 640px) {

  body {
    font-size: 15px;
  }

  h1 { font-size: 24px; }
  h2 { font-size: 20px; }
  h3 { font-size: 17px; }

  .brand {
    font-size: 18px;
  }

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

  .page-header {
    padding: 20px 0 24px;
    margin-bottom: 32px;
  }

  .hero-media {
    height: 340px;
  }

  .hero-overlay {
    padding: 0 16px;
    justify-content: flex-end;
    padding-bottom: 32px;
    background-color: rgba(31, 58, 46, 0.62);
  }

  .hero-title {
    font-size: 23px;
    margin-bottom: 12px;
  }

  .hero-lead {
    font-size: 15px;
    margin-bottom: 20px;
  }

  .hero-actions {
    width: 100%;
  }

  .hero-actions .btn {
    flex: 1 1 auto;
    min-width: 0;
    padding: 0 14px;
  }

  .channel-overview,
  .collection-preview,
  .field-summary,
  .browse-steps,
  .page-index {
    padding: 40px 16px;
  }

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

  .channel-row,
  .channel-list-section .channel-row {
    grid-template-columns: 1fr;
    gap: 10px;
  }

  .channel-row .channel-field,
  .channel-row .channel-scene {
    grid-column: auto;
  }

  .channel-figure {
    width: 100%;
    max-width: 320px;
  }

  .collection-grid {
    grid-template-columns: 1fr;
  }

  .index-columns {
    grid-template-columns: 1fr;
  }

  .scope-groups {
    grid-template-columns: 1fr;
  }

  .boundary-pair,
  .boundary-columns {
    grid-template-columns: 1fr;
  }

  .field-boundary-section .boundary-list {
    grid-template-columns: 1fr;
  }

  .feedback-grid {
    grid-template-columns: 1fr;
  }

  .collection-item .collection-card {
    grid-template-columns: 1fr;
  }

  .collection-item .collection-cover {
    width: 100%;
    min-height: 0;
    aspect-ratio: 16 / 9;
  }

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

  .field-table thead th,
  .field-table tbody th,
  .field-table tbody td {
    padding: 10px 12px;
    white-space: normal;
  }

  .field-table tbody td:last-child {
    font-size: 12px;
  }

  .step-no,
  .step-index {
    width: 36px;
    height: 36px;
    font-size: 15px;
  }

  .step-item,
  .path-steps .step-item {
    gap: 14px;
  }

  .footer-groups {
    grid-template-columns: 1fr;
    gap: 20px;
  }

  .footer-bottom {
    flex-direction: column;
    gap: 6px;
  }

  .error-code {
    font-size: 48px;
  }

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

  .error-actions {
    flex-direction: column;
    align-items: stretch;
  }

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

/* ============================================================
   print — browse-path
   ============================================================ */

@media print {

  .site-header,
  .site-footer,
  .breadcrumb,
  .print-action,
  .nav-toggle {
    display: none !important;
  }

  body {
    background-color: #FFFFFF;
    color: #000000;
  }

  .inner-main {
    max-width: 100%;
    padding: 0;
  }

  .faq-item {
    border: 1px solid #CCCCCC;
    break-inside: avoid;
  }

  .faq-answer {
    display: block;
  }

  a {
    color: #000000;
    border-bottom: none;
  }
}