:root {
  --ink: #0f0f10;
  --ink-soft: #5b5f66;
  --line: #e4e4e7;
  --line-soft: #f4f4f5;
  --paper: #ffffff;
  --accent: #c8102e;
  --radius: 6px;
  --wrap: 1120px;
  --read: 760px;
}

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

* {
  box-sizing: border-box;
}

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

body.site-body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Source Han Sans SC", sans-serif;
  font-size: 16px;
  line-height: 1.75;
  letter-spacing: 0;
}

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

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

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

h1,
h2,
h3 {
  margin: 0;
  font-weight: 600;
  line-height: 1.35;
}

p {
  margin: 0 0 12px;
}

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

dl,
dd,
figure,
figcaption,
table,
caption,
thead,
tbody,
tr,
th,
td,
time {
  margin: 0;
}

button {
  font: inherit;
  color: inherit;
}

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

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

.site-header,
.site-footer,
.site-main {
  width: 100%;
}

.header-inner,
.footer-inner,
.home-main,
.inner-main,
.error-inner {
  width: 100%;
  max-width: var(--wrap);
  margin: 0 auto;
  padding-left: 20px;
  padding-right: 20px;
}

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

.page-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 32px;
  align-items: start;
}

.page-content,
.content-main,
.guide-main {
  min-width: 0;
}

/* ============ header / nav ============ */

.site-header {
  border-bottom: 1px solid var(--line);
  background: var(--paper);
}

.header-inner {
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
  padding-top: 14px;
  padding-bottom: 14px;
}

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

.brand-name {
  font-size: 19px;
  font-weight: 700;
  color: var(--ink);
}

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

.site-nav {
  min-width: 0;
}

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

.nav-list li a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 12px;
  font-size: 15px;
  color: var(--ink-soft);
  border-bottom: 2px solid transparent;
}

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

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

.nav-toggle {
  display: none;
  flex-direction: column;
  justify-content: center;
  gap: 4px;
  width: 44px;
  height: 44px;
  padding: 0 10px;
  background: var(--paper);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  cursor: pointer;
}

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

/* ============ top bar ============ */

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

.top-bar p {
  max-width: var(--wrap);
  margin: 0 auto;
  padding: 8px 20px;
  font-size: 13px;
  color: var(--ink-soft);
}

/* ============ breadcrumb / page header ============ */

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

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

.breadcrumb a:hover {
  color: var(--accent);
}

.breadcrumb-sep {
  color: #b6b8bd;
}

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

.page-header {
  padding-bottom: 24px;
  margin-bottom: 28px;
  border-bottom: 1px solid var(--line);
}

.page-title {
  font-size: 30px;
  font-weight: 700;
  color: var(--ink);
}

.page-description {
  margin: 10px 0 0;
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

.page-lead {
  margin: 12px 0 0;
  max-width: var(--read);
  font-size: 16px;
  color: var(--ink);
}

/* ============ generic section ============ */

.section {
  padding: 32px 0;
  border-top: 1px solid var(--line);
}

.home-main .section:first-of-type,
.section:first-child {
  border-top: 0;
}

.section-head {
  margin-bottom: 18px;
}

.section-title,
.section-head h2 {
  font-size: 22px;
  font-weight: 600;
  color: var(--ink);
}

.section-head p,
.section-desc,
.section-intro,
.section-note {
  margin: 8px 0 0;
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

.section-more {
  margin: 16px 0 0;
  font-size: 15px;
}

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

.section-more a:hover {
  border-bottom-color: var(--accent);
}

.section-tail {
  margin-top: 16px;
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  font-size: 15px;
}

.section-tail a {
  color: var(--accent);
}

.subsection-title {
  font-size: 18px;
  font-weight: 600;
}

/* ============ figures / media ============ */

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

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

.hero-media {
  width: 100%;
  aspect-ratio: 16 / 10;
  overflow: hidden;
}

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

.content-media {
  width: 100%;
  margin: 0;
}

.content-media img {
  width: 100%;
  aspect-ratio: 16 / 9;
}

.content-media-primary img {
  aspect-ratio: 21 / 9;
}

.content-media-inline {
  max-width: var(--read);
  margin: 18px 0 0;
}

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

.section-figure {
  margin: 0 0 22px;
}

.section-figure img {
  width: 100%;
  aspect-ratio: 21 / 9;
}

.fields-figure {
  margin: 0 0 22px;
}

.fields-figure img {
  width: 100%;
  aspect-ratio: 21 / 9;
}

.media-figure {
  margin: 0 0 24px;
}

.media-figure img {
  width: 100%;
  aspect-ratio: 21 / 9;
}

.collection-media {
  margin: 0;
}

.collection-media img {
  width: 100%;
  aspect-ratio: 4 / 3;
}

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

.hero-section {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 32px;
  padding: 36px 0 40px;
  border-bottom: 1px solid var(--line);
}

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

.hero-kicker {
  margin: 0 0 12px;
  font-size: 13px;
  font-weight: 600;
  color: var(--accent);
}

.hero-title {
  font-size: 30px;
  font-weight: 700;
  color: var(--ink);
}

.hero-text {
  margin: 14px 0 0;
  max-width: 560px;
  font-size: 16px;
  color: var(--ink-soft);
}

.hero-paths {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin-top: 24px;
}

.hero-path {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.hero-path-label {
  font-size: 13px;
  color: var(--ink-soft);
}

.hero-path a {
  font-size: 15px;
  font-weight: 600;
  color: var(--accent);
}

.hero-media,
.content-media-primary {
  grid-column: 2;
}

.hero-copy {
  grid-column: 1;
  grid-row: 1 / span 2;
}

.hero-media {
  grid-row: 1;
}

.content-media-primary {
  grid-row: 2;
}

/* ============ home: channel rows ============ */

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

.channel-row {
  display: grid;
  grid-template-columns: minmax(140px, 200px) minmax(0, 1fr) minmax(0, 1fr);
  gap: 16px;
  align-items: baseline;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.channel-name {
  font-size: 17px;
  font-weight: 600;
  color: var(--ink);
}

.channel-tendency,
.channel-organize {
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ home: collections ============ */

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

.collection-card {
  display: flex;
  flex-direction: column;
  gap: 8px;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--paper);
}

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

.collection-name {
  font-size: 18px;
  font-weight: 600;
}

.collection-scope,
.collection-clue {
  font-size: 15px;
  color: var(--ink-soft);
  margin: 0;
}

.collection-more {
  margin: auto 0 0;
  padding-top: 6px;
  font-size: 15px;
}

.collection-more a {
  color: var(--accent);
}

/* ============ home: fields summary ============ */

.fields-layout {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr);
  gap: 32px;
  align-items: start;
}

.fields-column h3,
.bounds-column h3 {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 12px;
}

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

.field-list dt {
  padding-top: 10px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.field-list dd {
  padding-bottom: 10px;
  font-size: 15px;
  color: var(--ink-soft);
  border-bottom: 1px solid var(--line);
}

.bounds-column p {
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ home: path steps ============ */

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

.path-step {
  display: grid;
  grid-template-columns: 48px minmax(140px, 220px) minmax(0, 1fr);
  gap: 16px;
  align-items: baseline;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.step-index {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 15px;
  font-weight: 600;
  color: var(--accent);
}

.path-step .step-name {
  font-size: 17px;
  font-weight: 600;
}

.path-step .step-desc {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ home: site index ============ */

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

.index-cell {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.index-cell h3 {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.index-cell h3 a {
  color: var(--accent);
}

.index-cell p {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ inner: aside ============ */

.page-aside,
.content-aside,
.guide-sidebar,
.sidebar {
  min-width: 0;
  padding: 20px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--line-soft);
}

.aside-title,
.sidebar-title {
  font-size: 16px;
  font-weight: 600;
  margin-bottom: 8px;
}

.aside-note,
.sidebar-intro {
  margin: 0 0 12px;
  font-size: 14px;
  color: var(--ink-soft);
}

.aside-list,
.sidebar-list,
.sidebar-nav,
.sidebar-links {
  display: flex;
  flex-direction: column;
  gap: 2px;
  border-top: 1px solid var(--line);
  padding-top: 8px;
}

.aside-list li a,
.sidebar-list li a,
.sidebar-nav-item a,
.sidebar-links li a {
  display: block;
  padding: 8px 0;
  font-size: 15px;
  color: var(--ink);
  border-bottom: 1px solid var(--line);
}

.aside-list li a:hover,
.sidebar-list li a:hover,
.sidebar-nav-item a:hover,
.sidebar-links li a:hover {
  color: var(--accent);
}

.aside-extra {
  margin-top: 18px;
}

.aside-subtitle {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 6px;
}

/* ============ channels page ============ */

.sidebar-left .page-layout {
  grid-template-columns: 280px minmax(0, 1fr);
}

.channel-row-head {
  display: flex;
  align-items: baseline;
  gap: 12px;
}

.section-channel-table .channel-row {
  display: block;
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

.section-channel-table .channel-row:first-of-type {
  border-top: 1px solid var(--line);
}

.section-channel-table .channel-index {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 15px;
  font-weight: 600;
  color: var(--accent);
}

.channel-fields {
  display: grid;
  grid-template-columns: minmax(110px, 160px) minmax(0, 1fr);
  gap: 4px 16px;
  margin-top: 12px;
}

.channel-fields dt {
  font-size: 14px;
  color: var(--ink-soft);
}

.channel-fields dd {
  font-size: 15px;
  color: var(--ink);
}

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

.compare-col {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.compare-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.compare-text {
  font-size: 15px;
  color: var(--ink-soft);
}

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

.advice-item {
  display: grid;
  grid-template-columns: 48px minmax(140px, 220px) minmax(0, 1fr);
  gap: 16px;
  align-items: baseline;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.advice-index {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 15px;
  font-weight: 600;
  color: var(--accent);
}

.advice-title {
  font-size: 17px;
  font-weight: 600;
}

.advice-text {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

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

.mapping-item {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.mapping-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.mapping-text {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ collections page ============ */

.layout-shell {
  grid-template-columns: minmax(0, 1fr) 300px;
}

.layout-shell .content-main {
  order: 1;
}

.layout-shell .content-aside,
.layout-shell .sidebar-right {
  order: 2;
}

.collection-block {
  display: grid;
  grid-template-columns: 260px minmax(0, 1fr);
  gap: 24px;
  align-items: start;
  padding: 24px 0;
  border-top: 1px solid var(--line);
}

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

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

.collection-fit {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

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

.logic-item {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.logic-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.logic-item p {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

.mapping-table {
  width: 100%;
  border-collapse: collapse;
  font-size: 15px;
}

.mapping-caption {
  text-align: left;
  padding-bottom: 10px;
  font-size: 14px;
  color: var(--ink-soft);
}

.mapping-table th,
.mapping-table td {
  text-align: left;
  padding: 12px 14px;
  border-bottom: 1px solid var(--line);
  vertical-align: top;
}

.mapping-table thead th {
  background: var(--line-soft);
  font-weight: 600;
  color: var(--ink);
}

.mapping-table tbody td {
  color: var(--ink-soft);
}

.mapping-table tbody td:first-child {
  color: var(--ink);
  font-weight: 600;
}

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

.order-item {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr);
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.order-index {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 15px;
  font-weight: 600;
  color: var(--accent);
}

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

.order-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 6px;
}

.order-body p {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ fields page ============ */

.fields-layout {
  grid-template-columns: minmax(0, 1fr) 300px;
}

.field-table {
  border-top: 1px solid var(--line);
}

.field-row {
  display: grid;
  grid-template-columns: minmax(120px, 200px) minmax(0, 1fr);
  gap: 16px;
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.field-row-head {
  border-bottom: 2px solid var(--ink);
}

.field-row-head .field-name,
.field-row-head .field-desc {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.field-name {
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.field-desc {
  font-size: 15px;
  color: var(--ink-soft);
}

.boundary-section,
.combo-section,
.misread-section {
  padding: 32px 0;
  border-top: 1px solid var(--line);
}

.boundary-block {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  margin-bottom: 16px;
}

.boundary-block h3 {
  margin-bottom: 8px;
}

.boundary-block p {
  font-size: 15px;
  color: var(--ink-soft);
}

.boundary-list {
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.boundary-list li {
  position: relative;
  padding-left: 16px;
  font-size: 15px;
  color: var(--ink-soft);
}

.boundary-list li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 11px;
  width: 6px;
  height: 6px;
  background: var(--accent);
  border-radius: 1px;
}

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

.combo-item {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.combo-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.combo-text {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

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

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

.misread-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 6px;
}

.misread-item p {
  margin: 0;
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

/* ============ guide page ============ */

.layout-tutorial {
  grid-template-columns: minmax(0, 1fr) 300px;
}

.guide-main {
  order: 1;
}

.guide-sidebar {
  order: 2;
}

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

.step-item {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr);
  gap: 8px 16px;
  padding: 18px 0;
  border-bottom: 1px solid var(--line);
}

.step-item .step-index {
  grid-row: 1 / span 3;
}

.step-title {
  font-size: 18px;
  font-weight: 600;
}

.step-desc,
.step-result {
  margin: 0;
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

.step-result {
  color: var(--ink);
}

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

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

.faq-question {
  padding: 16px 32px 16px 0;
  position: relative;
  font-size: 16px;
  font-weight: 600;
  cursor: pointer;
  list-style: none;
}

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

.faq-question::after {
  content: "+";
  position: absolute;
  right: 4px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 20px;
  color: var(--accent);
}

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

.faq-answer {
  margin: 0;
  padding: 0 0 16px;
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

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

.alternative-item {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.alternative-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.alternative-desc {
  margin: 0;
  font-size: 15px;
  color: var(--ink-soft);
}

.section-boundary .section-paragraph {
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

.guide-sidebar .sidebar-title + .sidebar-nav {
  margin-bottom: 18px;
}

/* ============ corrections page ============ */

.timeline-list {
  position: relative;
  border-left: 2px solid var(--line);
  padding-left: 22px;
}

.timeline-item {
  position: relative;
  padding: 0 0 22px;
}

.timeline-item::before {
  content: "";
  position: absolute;
  left: -29px;
  top: 8px;
  width: 10px;
  height: 10px;
  background: var(--accent);
  border-radius: 50%;
}

.timeline-date {
  display: block;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 14px;
  color: var(--accent);
}

.timeline-title {
  font-size: 17px;
  font-weight: 600;
  margin: 4px 0 6px;
}

.timeline-text {
  margin: 0;
  max-width: var(--read);
  font-size: 15px;
  color: var(--ink-soft);
}

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

.reason-item {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
}

.reason-title {
  font-size: 17px;
  font-weight: 600;
  margin-bottom: 8px;
}

.reason-cause,
.reason-scope {
  margin: 0 0 6px;
  font-size: 15px;
  color: var(--ink-soft);
}

.reason-label {
  display: inline-block;
  margin-right: 6px;
  padding: 0 6px;
  font-size: 13px;
  color: var(--accent);
  border: 1px solid var(--accent);
  border-radius: 3px;
}

.contrast-table {
  border-top: 1px solid var(--line);
}

.contrast-row {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 1fr) minmax(0, 1fr);
  gap: 16px;
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
}

.contrast-head .contrast-cell {
  font-size: 14px;
  font-weight: 600;
  color: var(--ink);
}

.contrast-cell {
  font-size: 15px;
  color: var(--ink-soft);
}

.feedback-list {
  display: flex;
  flex-direction: column;
  gap: 8px;
  border-top: 1px solid var(--line);
  padding-top: 12px;
}

.feedback-item a {
  display: inline-block;
  padding: 6px 0;
  font-size: 15px;
  color: var(--accent);
  border-bottom: 1px solid transparent;
}

.feedback-item a:hover {
  border-bottom-color: var(--accent);
}

/* ============ 404 ============ */

.error-main {
  padding-top: 48px;
  padding-bottom: 64px;
}

.error-inner {
  max-width: var(--read);
}

.error-code {
  margin: 0 0 8px;
  font-family: "SFMono-Regular", Consolas, "Liberation Mono", Menlo, monospace;
  font-size: 15px;
  font-weight: 600;
  color: var(--accent);
}

.error-main h1 {
  font-size: 30px;
  font-weight: 700;
}

.error-lead {
  margin: 12px 0 32px;
  font-size: 16px;
  color: var(--ink-soft);
}

.error-section {
  padding: 24px 0;
  border-top: 1px solid var(--line);
}

.error-section h2 {
  font-size: 20px;
  font-weight: 600;
  margin-bottom: 12px;
}

.error-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.error-list li a {
  display: inline-block;
  padding: 6px 0;
  font-size: 15px;
  color: var(--accent);
  border-bottom: 1px solid transparent;
}

.error-list li a:hover {
  border-bottom-color: var(--accent);
}

.error-actions {
  margin: 32px 0 0;
}

.error-button {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 20px;
  font-size: 15px;
  font-weight: 600;
  color: var(--paper);
  background: var(--accent);
  border-radius: var(--radius);
}

.error-button:hover {
  color: var(--paper);
  background: #a50d26;
}

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

.site-footer {
  margin-top: 40px;
  border-top: 1px solid var(--line);
  background: var(--line-soft);
}

.footer-inner {
  padding-top: 36px;
  padding-bottom: 28px;
}

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

.footer-title {
  font-size: 15px;
  font-weight: 600;
  margin-bottom: 10px;
}

.footer-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
}

.footer-list li a {
  display: inline-block;
  padding: 4px 0;
  font-size: 14px;
  color: var(--ink-soft);
}

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

.footer-boundary {
  margin: 28px 0 0;
  padding-top: 18px;
  border-top: 1px solid var(--line);
  font-size: 13px;
  color: var(--ink-soft);
}

.footer-copy {
  margin: 8px 0 0;
  font-size: 13px;
  color: var(--ink-soft);
}

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

@media (max-width: 1024px) {
  .index-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .mapping-list,
  .logic-grid,
  .combo-grid,
  .alternative-list,
  .collection-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

@media (max-width: 900px) {
  .layout-shell,
  .fields-layout,
  .layout-tutorial,
  .sidebar-left .page-layout {
    grid-template-columns: minmax(0, 1fr);
  }

  .layout-shell .content-aside,
  .layout-shell .sidebar-right,
  .guide-sidebar,
  .fields-aside {
    order: 3;
  }

  .sidebar-left .page-aside {
    order: 3;
  }

  .page-layout {
    gap: 24px;
  }

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

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

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

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    width: 100%;
    border-top: 1px solid var(--line);
    padding-top: 4px;
  }

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

  .nav-list li a {
    padding: 0 4px;
    border-bottom: 1px solid var(--line);
    border-left: 2px solid transparent;
  }

  .nav-list li a.is-current {
    border-left-color: var(--accent);
    border-bottom-color: var(--line);
  }

  .hero-section {
    grid-template-columns: minmax(0, 1fr);
    gap: 24px;
    padding: 28px 0 32px;
  }

  .hero-copy {
    grid-column: 1;
    grid-row: auto;
  }

  .hero-media {
    grid-column: 1;
    grid-row: auto;
    order: -1;
  }

  .content-media-primary {
    grid-column: 1;
    grid-row: auto;
  }

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

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

  .path-step,
  .advice-item {
    grid-template-columns: 40px minmax(0, 1fr);
    gap: 4px 12px;
  }

  .path-step .step-name,
  .advice-title {
    grid-column: 2;
  }

  .path-step .step-desc,
  .advice-text {
    grid-column: 2;
  }

  .fields-layout,
  .compare-columns,
  .reason-list,
  .collection-grid,
  .mapping-list,
  .logic-grid,
  .combo-grid,
  .alternative-list {
    grid-template-columns: minmax(0, 1fr);
  }

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

  .field-row-head {
    display: none;
  }

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

  .channel-fields {
    grid-template-columns: minmax(0, 1fr);
    gap: 2px;
  }

  .channel-fields dt {
    margin-top: 8px;
  }

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

  .mapping-table,
  .mapping-table thead,
  .mapping-table tbody,
  .mapping-table tr,
  .mapping-table th,
  .mapping-table td {
    display: block;
    width: 100%;
  }

  .mapping-table thead {
    display: none;
  }

  .mapping-table tr {
    padding: 12px 0;
    border-bottom: 1px solid var(--line);
  }

  .mapping-table th,
  .mapping-table td {
    padding: 2px 0;
    border: 0;
  }
}

@media (max-width: 560px) {
  .header-inner,
  .footer-inner,
  .home-main,
  .inner-main,
  .error-inner,
  .top-bar p {
    padding-left: 16px;
    padding-right: 16px;
  }

  body.site-body {
    font-size: 15px;
  }

  .page-title,
  .hero-title,
  .error-main h1 {
    font-size: 24px;
  }

  .section-title,
  .section-head h2 {
    font-size: 20px;
  }

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

  .step-item {
    grid-template-columns: 40px minmax(0, 1fr);
  }

  .order-item {
    grid-template-columns: 40px minmax(0, 1fr);
    gap: 12px;
  }

  .footer-groups {
    grid-template-columns: minmax(0, 1fr);
    gap: 18px;
  }
}