:root {
  --color-primary: #0f6f74;
  --color-primary-dark: #0b565a;
  --color-accent: #e6f2f3;
  --color-text: #24313a;
  --color-muted: #5c6b73;
  --color-bg: #f7fafb;
  --color-surface: #ffffff;
  --color-border: #d6e2e5;
  --shadow-soft: 0 1px 2px rgba(15, 111, 116, 0.06);
  --shadow-card: 0 2px 8px rgba(15, 111, 116, 0.08);
  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --container: 1120px;
  --header-height: 64px;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
}

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

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

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  scroll-behavior: smooth;
}

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

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

p {
  margin: 0;
}

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

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

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

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

figure {
  margin: 0;
}

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

time {
  font-style: normal;
}

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

.site-body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  background-color: var(--color-bg);
}

.site-main {
  flex: 1 0 auto;
  width: 100%;
}

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

.home-main {
  width: 100%;
}

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

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  background-color: var(--color-surface);
  border-bottom: 1px solid var(--color-border);
}

.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  height: var(--header-height);
  padding: 0 24px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
}

.brand {
  display: inline-flex;
  align-items: center;
  height: 40px;
  padding: 0 4px;
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text);
  white-space: nowrap;
  letter-spacing: 0;
}

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

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

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

.site-nav {
  display: block;
}

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

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

.nav-link {
  display: inline-flex;
  align-items: center;
  height: 40px;
  padding: 0 14px;
  border-radius: var(--radius-md);
  font-size: 15px;
  color: var(--color-text);
  white-space: nowrap;
}

.nav-link:hover {
  color: var(--color-primary);
  background-color: var(--color-accent);
}

.nav-link.is-current {
  color: var(--color-primary);
  background-color: var(--color-accent);
  font-weight: 600;
}

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

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

.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 48px 24px 32px;
  display: grid;
  grid-template-columns: 1.5fr 1fr 1fr 1fr;
  gap: 32px;
}

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

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

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

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

.footer-links a {
  display: inline-block;
  font-size: 14px;
  color: var(--color-muted);
  line-height: 1.6;
}

.footer-links a:hover {
  color: var(--color-primary);
}

.footer-bottom {
  max-width: var(--container);
  margin: 0 auto;
  padding: 20px 24px 28px;
  border-top: 1px solid var(--color-border);
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 8px 20px;
}

.footer-brand {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-text);
}

.footer-slogan,
.footer-copy {
  font-size: 13px;
  color: var(--color-muted);
}

.footer-copy {
  margin-left: auto;
}

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

.section {
  max-width: var(--container);
  margin: 0 auto;
  padding: 56px 24px;
}

.section-head {
  margin-bottom: 28px;
}

.section-title {
  font-size: 24px;
  font-weight: 600;
  color: var(--color-text);
}

.section-desc,
.section-intro,
.section-lead {
  margin-top: 10px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-muted);
}

.text-link {
  display: inline-flex;
  align-items: center;
  gap: 4px;
  font-size: 15px;
  font-weight: 600;
  color: var(--color-primary);
}

.text-link::after {
  content: "→";
  font-size: 14px;
}

.text-link:hover {
  color: var(--color-primary-dark);
}

.inline-link {
  color: var(--color-primary);
  text-decoration: underline;
  text-underline-offset: 3px;
}

.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 22px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  white-space: nowrap;
}

.btn-primary {
  color: #ffffff;
  background-color: var(--color-primary);
  border: 1px solid var(--color-primary);
}

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

.btn-ghost {
  color: #ffffff;
  background-color: rgba(255, 255, 255, 0.12);
  border: 1px solid rgba(255, 255, 255, 0.55);
}

.btn-ghost:hover {
  color: #ffffff;
  background-color: rgba(255, 255, 255, 0.24);
  border-color: #ffffff;
}

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

.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 20px 0 0;
  font-size: 14px;
  color: var(--color-muted);
}

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

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

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

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

.page-header {
  padding: 20px 0 8px;
}

.page-title {
  font-size: 30px;
  font-weight: 600;
  color: var(--color-text);
}

.page-description {
  margin-top: 12px;
  max-width: 820px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-muted);
}

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

.hero {
  position: relative;
  width: 100%;
  min-height: 420px;
  display: flex;
  align-items: flex-end;
  overflow: hidden;
  background-color: #0b3b3e;
}

.hero-media {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
}

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

.hero-overlay {
  position: relative;
  z-index: 1;
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 72px 24px 48px;
  background-color: rgba(11, 42, 44, 0.62);
}

.hero-kicker {
  display: inline-block;
  padding: 4px 12px;
  margin-bottom: 16px;
  border-radius: var(--radius-sm);
  font-size: 13px;
  color: #ffffff;
  background-color: rgba(15, 111, 116, 0.85);
}

.hero-title {
  max-width: 720px;
  font-size: 34px;
  font-weight: 600;
  line-height: 1.3;
  color: #ffffff;
}

.hero-desc {
  max-width: 720px;
  margin-top: 14px;
  font-size: 16px;
  line-height: 1.8;
  color: rgba(255, 255, 255, 0.88);
}

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

/* ===================== home: channels ===================== */

.channel-list {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.channel-row {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr) auto;
  align-items: center;
  gap: 20px;
  padding: 20px 24px;
  border-bottom: 1px solid var(--color-border);
  transition: background-color 0.18s ease;
}

.channel-row:last-child {
  border-bottom: none;
}

.channel-row:hover {
  background-color: var(--color-accent);
}

.channel-no {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  color: var(--color-primary);
  background-color: var(--color-accent);
}

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

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

.channel-topic,
.channel-rep {
  margin-top: 6px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-muted);
}

.channel-rep {
  color: var(--color-text);
}

.channel-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-md);
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
  background-color: var(--color-surface);
  white-space: nowrap;
}

.channel-link:hover {
  color: #ffffff;
  background-color: var(--color-primary);
  border-color: var(--color-primary);
}

/* ===================== home: topics ===================== */

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

.topic-card {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
  transition: border-color 0.18s ease, box-shadow 0.18s ease;
}

.topic-card:hover {
  border-color: var(--color-primary);
  box-shadow: var(--shadow-card);
}

.topic-media {
  width: 100%;
  aspect-ratio: 16 / 9;
  overflow: hidden;
  background-color: var(--color-accent);
}

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

.topic-body {
  display: flex;
  flex-direction: column;
  flex: 1 1 auto;
  padding: 20px 22px 22px;
}

.topic-name {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text);
}

.topic-judge {
  margin-top: 10px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.topic-count {
  margin-top: 12px;
  font-size: 13px;
  color: var(--color-primary);
}

.topic-link {
  margin-top: auto;
  padding-top: 16px;
  font-size: 14px;
  font-weight: 600;
}

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

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

.step-item {
  padding: 22px 20px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
}

.step-no {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  margin-bottom: 14px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  color: #ffffff;
  background-color: var(--color-primary);
}

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

.step-cond {
  margin-top: 8px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-muted);
}

.steps-more,
.records-more {
  margin-top: 24px;
  font-size: 15px;
}

/* ===================== home: boundary ===================== */

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

.boundary-card {
  padding: 26px 24px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-accent);
}

.boundary-name {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text);
}

.boundary-text {
  margin-top: 10px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.boundary-points {
  margin-top: 16px;
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.boundary-points li {
  position: relative;
  padding-left: 18px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-text);
}

.boundary-points li::before {
  content: "";
  position: absolute;
  left: 0;
  top: 10px;
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background-color: var(--color-primary);
}

.boundary-more {
  margin-top: 20px;
  font-size: 15px;
}

/* ===================== home: records ===================== */

.record-months {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 24px;
}

.record-month {
  padding: 22px 22px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
}

.record-month-name {
  padding-bottom: 12px;
  margin-bottom: 12px;
  border-bottom: 1px solid var(--color-border);
  font-size: 16px;
  font-weight: 600;
  color: var(--color-primary);
}

.record-list {
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.record-item {
  min-width: 0;
}

.record-date {
  display: inline-block;
  font-size: 13px;
  color: var(--color-muted);
}

.record-channel {
  display: inline-block;
  margin-left: 8px;
  padding: 1px 8px;
  border-radius: var(--radius-sm);
  font-size: 12px;
  color: var(--color-primary);
  background-color: var(--color-accent);
}

.record-summary {
  margin-top: 4px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-text);
}

/* ===================== home: sitelinks ===================== */

.sitelink-grid {
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 16px;
}

.sitelink {
  display: flex;
  flex-direction: column;
  gap: 6px;
  padding: 20px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  transition: border-color 0.18s ease, background-color 0.18s ease;
}

.sitelink:hover {
  border-color: var(--color-primary);
  background-color: var(--color-accent);
}

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

.sitelink-desc {
  font-size: 13px;
  line-height: 1.7;
  color: var(--color-muted);
}

/* ===================== inner: channels page ===================== */

.channels-overview,
.channel-entry-types,
.channel-topic-mapping {
  padding-top: 40px;
}

.overview-media {
  margin: 20px 0 28px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background-color: var(--color-surface);
}

.overview-media img {
  width: 100%;
  aspect-ratio: 21 / 9;
  object-fit: cover;
}

.overview-caption {
  padding: 12px 18px;
  font-size: 13px;
  color: var(--color-muted);
  border-top: 1px solid var(--color-border);
}

.channel-rows {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.channel-desc {
  margin-top: 8px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.channel-meta {
  margin-top: 8px;
  font-size: 13px;
  color: var(--color-primary);
}

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

.entry-type {
  padding: 22px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
}

.entry-type-name {
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text);
}

.entry-type-desc {
  margin-top: 10px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.mapping-rows {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.mapping-row {
  display: grid;
  grid-template-columns: 140px minmax(0, 1fr);
  align-items: center;
  gap: 20px;
  padding: 18px 24px;
  border-bottom: 1px solid var(--color-border);
}

.mapping-row:last-child {
  border-bottom: none;
}

.mapping-channel {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-primary);
}

.mapping-topic {
  font-size: 15px;
  color: var(--color-text);
}

.mapping-note {
  margin-top: 18px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.mapping-note a {
  margin-right: 4px;
}

/* ===================== inner: topics page ===================== */

.topic-center,
.topic-items,
.topic-order {
  padding-top: 40px;
}

.topic-center-item {
  padding: 22px 24px;
  border: 1px solid var(--color-border);
  border-left: 4px solid var(--color-primary);
  border-radius: var(--radius-md);
  background-color: var(--color-surface);
}

.topic-center-item + .topic-center-item {
  margin-top: 16px;
}

.topic-center-name {
  font-size: 17px;
  font-weight: 600;
  color: var(--color-text);
}

.topic-center-judge {
  margin-top: 10px;
  font-size: 15px;
  line-height: 1.8;
  color: var(--color-text);
}

.topic-center-reason {
  margin-top: 8px;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-muted);
}

.topic-figure {
  margin: 22px 0 28px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background-color: var(--color-surface);
}

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

.topic-figure-caption {
  padding: 12px 18px;
  font-size: 13px;
  color: var(--color-muted);
  border-top: 1px solid var(--color-border);
}

.topic-group + .topic-group {
  margin-top: 28px;
}

.topic-group-name {
  margin-bottom: 14px;
  font-size: 17px;
  font-weight: 600;
  color: var(--color-primary);
}

.topic-item-list {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.topic-item {
  display: grid;
  grid-template-columns: 48px minmax(0, 1fr) 120px;
  align-items: center;
  gap: 8px 18px;
  padding: 16px 22px;
  border-bottom: 1px solid var(--color-border);
}

.topic-item:last-child {
  border-bottom: none;
}

.topic-item-index {
  font-size: 14px;
  font-weight: 600;
  color: var(--color-primary);
}

.topic-item-name {
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
}

.topic-item-channel {
  justify-self: end;
  padding: 2px 10px;
  border-radius: var(--radius-sm);
  font-size: 12px;
  color: var(--color-primary);
  background-color: var(--color-accent);
  white-space: nowrap;
}

.topic-item-note {
  grid-column: 2 / -1;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-muted);
}

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

.topic-order-col {
  padding: 24px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
}

.topic-order-heading {
  font-size: 17px;
  font-weight: 600;
  color: var(--color-text);
}

.topic-order-text {
  margin-top: 12px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

/* ===================== inner: guide page ===================== */

.guide-steps,
.guide-conditions,
.guide-check,
.guide-faq,
.guide-next {
  padding-top: 40px;
}

.guide-steps .step-list {
  grid-template-columns: repeat(4, minmax(0, 1fr));
}

.guide-steps .step-item {
  display: flex;
  flex-direction: column;
  padding: 0 0 22px;
  overflow: hidden;
}

.step-figure {
  width: 100%;
  aspect-ratio: 4 / 3;
  margin-bottom: 16px;
  overflow: hidden;
  background-color: var(--color-accent);
}

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

.guide-steps .step-index {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  margin: 0 20px 12px;
  border-radius: var(--radius-md);
  font-size: 15px;
  font-weight: 600;
  color: #ffffff;
  background-color: var(--color-primary);
}

.guide-steps .step-name {
  margin: 0 20px;
  font-size: 16px;
}

.guide-steps .step-text {
  margin: 8px 20px 0;
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-muted);
}

.guide-steps .step-state {
  margin: 12px 20px 0;
  padding-top: 10px;
  border-top: 1px dashed var(--color-border);
  font-size: 13px;
  color: var(--color-primary);
}

.condition-list {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.condition-item {
  padding: 18px 24px;
  border-bottom: 1px solid var(--color-border);
}

.condition-item:last-child {
  border-bottom: none;
}

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

.condition-text {
  margin-top: 6px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

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

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

.column-title {
  font-size: 17px;
  font-weight: 600;
  color: var(--color-text);
}

.check-list {
  margin-top: 14px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.check-item {
  position: relative;
  padding-left: 22px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.check-item::before {
  content: "";
  position: absolute;
  left: 0;
  top: 9px;
  width: 8px;
  height: 8px;
  border: 2px solid var(--color-primary);
  border-radius: 50%;
}

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

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

.faq-question {
  position: relative;
  padding: 18px 52px 18px 22px;
  font-size: 16px;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  list-style: none;
}

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

.faq-question::after {
  content: "+";
  position: absolute;
  right: 22px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 20px;
  font-weight: 400;
  color: var(--color-primary);
}

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

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

.faq-answer {
  padding: 0 22px 20px;
  font-size: 14px;
  line-height: 1.85;
  color: var(--color-muted);
}

.next-list {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.next-item a {
  display: flex;
  align-items: center;
  min-height: 60px;
  padding: 14px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  background-color: var(--color-surface);
  transition: border-color 0.18s ease, background-color 0.18s ease, color 0.18s ease;
}

.next-item a:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background-color: var(--color-accent);
}

/* ===================== inner: records page ===================== */

.records-intro {
  padding-top: 40px;
}

.records-figure {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  overflow: hidden;
  background-color: var(--color-surface);
}

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

.records-figure figcaption {
  padding: 12px 18px;
  font-size: 13px;
  color: var(--color-muted);
  border-top: 1px solid var(--color-border);
}

.records-intro-text {
  margin-top: 20px;
  font-size: 15px;
  line-height: 1.85;
  color: var(--color-muted);
}

.records-intro-text a {
  margin-right: 4px;
}

.records-monthly,
.records-columns,
.records-boundary,
.records-links {
  padding-top: 40px;
}

.month-group {
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.month-group + .month-group {
  margin-top: 16px;
}

.month-summary {
  position: relative;
  padding: 18px 52px 18px 22px;
  font-size: 17px;
  font-weight: 600;
  color: var(--color-text);
  cursor: pointer;
  list-style: none;
}

.month-summary::-webkit-details-marker {
  display: none;
}

.month-summary::after {
  content: "+";
  position: absolute;
  right: 22px;
  top: 50%;
  transform: translateY(-50%);
  font-size: 20px;
  font-weight: 400;
  color: var(--color-primary);
}

.month-group[open] .month-summary::after {
  content: "–";
}

.month-group[open] .month-summary {
  color: var(--color-primary);
}

.month-group .record-list {
  padding: 4px 22px 20px;
  gap: 0;
}

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

.record-column {
  font-size: 13px;
  color: var(--color-primary);
}

.record-type {
  font-size: 13px;
  color: var(--color-muted);
}

.record-text {
  font-size: 14px;
  line-height: 1.75;
  color: var(--color-text);
}

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

.column-card {
  padding: 22px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
}

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

.column-desc {
  margin-top: 10px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--color-muted);
}

.boundary-list {
  display: flex;
  flex-direction: column;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  overflow: hidden;
}

.boundary-item {
  padding: 18px 24px;
  border-bottom: 1px solid var(--color-border);
}

.boundary-item:last-child {
  border-bottom: none;
}

.boundary-date {
  display: inline-block;
  margin-bottom: 6px;
  font-size: 13px;
  color: var(--color-primary);
}

.related-links {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.related-item a {
  display: flex;
  align-items: center;
  min-height: 56px;
  padding: 14px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  background-color: var(--color-surface);
  transition: border-color 0.18s ease, background-color 0.18s ease, color 0.18s ease;
}

.related-item a:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background-color: var(--color-accent);
}

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

.error-main {
  max-width: var(--container);
  margin: 0 auto;
  padding: 64px 24px 72px;
}

.error-panel {
  padding: 40px 32px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  background-color: var(--color-surface);
  text-align: center;
}

.error-code {
  font-size: 40px;
  font-weight: 600;
  color: var(--color-primary);
}

.error-title {
  margin-top: 12px;
  font-size: 26px;
  font-weight: 600;
  color: var(--color-text);
}

.error-text {
  max-width: 560px;
  margin: 14px auto 0;
  font-size: 15px;
  line-height: 1.85;
  color: var(--color-muted);
}

.error-actions {
  margin-top: 26px;
  display: flex;
  justify-content: center;
}

.error-suggest {
  margin-top: 40px;
}

.error-links {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: 16px;
}

.error-links a {
  display: flex;
  align-items: center;
  min-height: 56px;
  padding: 14px 18px;
  border: 1px solid var(--color-border);
  border-radius: var(--radius-lg);
  font-size: 15px;
  font-weight: 600;
  color: var(--color-text);
  background-color: var(--color-surface);
  transition: border-color 0.18s ease, background-color 0.18s ease, color 0.18s ease;
}

.error-links a:hover {
  color: var(--color-primary);
  border-color: var(--color-primary);
  background-color: var(--color-accent);
}

/* ===================== motion enhancement ===================== */

.reveal {
  opacity: 1;
  transform: none;
}

@media (prefers-reduced-motion: no-preference) {
  .reveal.is-visible {
    animation: reveal-rise 0.45s ease-out both;
  }
}

@keyframes reveal-rise {
  from {
    opacity: 0.4;
    transform: translateY(10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

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

@media (max-width: 1024px) {
  .footer-inner {
    grid-template-columns: repeat(2, minmax(0, 1fr));
    gap: 28px;
  }

  .record-months,
  .columns-grid,
  .related-links,
  .error-links,
  .next-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

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

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

@media (max-width: 768px) {
  .header-inner {
    padding: 0 16px;
  }

  .nav-toggle {
    display: flex;
  }

  .site-nav {
    position: absolute;
    left: 0;
    right: 0;
    top: var(--header-height);
    background-color: var(--color-surface);
    border-bottom: 1px solid var(--color-border);
    box-shadow: var(--shadow-soft);
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 8px 16px 16px;
  }

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

  .nav-link {
    width: 100%;
    height: 48px;
    padding: 0 14px;
  }

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

  .section {
    padding: 40px 16px;
  }

  .hero {
    min-height: 340px;
  }

  .hero-overlay {
    padding: 48px 16px 32px;
  }

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

  .hero-desc {
    font-size: 15px;
  }

  .hero-actions {
    gap: 10px;
  }

  .btn {
    padding: 0 18px;
  }

  .page-header {
    padding: 16px 0 4px;
  }

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

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

  .channel-row {
    grid-template-columns: 44px minmax(0, 1fr);
    gap: 14px;
    padding: 18px 16px;
  }

  .channel-link {
    grid-column: 1 / -1;
    justify-self: start;
  }

  .topic-grid,
  .boundary-grid,
  .entry-type-list,
  .topic-order-columns,
  .check-columns {
    grid-template-columns: minmax(0, 1fr);
  }

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

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

  .mapping-row {
    grid-template-columns: minmax(0, 1fr);
    gap: 6px;
    padding: 16px;
  }

  .topic-item {
    grid-template-columns: 40px minmax(0, 1fr);
    padding: 14px 16px;
  }

  .topic-item-channel {
    grid-column: 2;
    justify-self: start;
  }

  .topic-item-note {
    grid-column: 2;
  }

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

  .month-group .record-list {
    padding: 4px 16px 16px;
  }

  .month-summary {
    padding: 16px 46px 16px 16px;
  }

  .faq-question {
    padding: 16px 46px 16px 16px;
    font-size: 15px;
  }

  .faq-answer {
    padding: 0 16px 18px;
  }

  .overview-caption,
  .topic-figure-caption,
  .records-figure figcaption {
    padding: 10px 14px;
  }

  .footer-inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 24px;
    padding: 36px 16px 24px;
  }

  .footer-bottom {
    padding: 18px 16px 24px;
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }

  .footer-copy {
    margin-left: 0;
  }

  .error-main {
    padding: 40px 16px 56px;
  }

  .error-panel {
    padding: 32px 20px;
  }

  .error-code {
    font-size: 34px;
  }

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

@media (max-width: 420px) {
  .sitelink-grid {
    grid-template-columns: minmax(0, 1fr);
  }

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

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

  .brand {
    font-size: 16px;
  }
}