/* ============================================================
   base
   ============================================================ */
:root {
  --bg-paper: #F7F5F0;
  --bg-card: #FFFFFF;
  --bg-soft: #EFEDE7;
  --ink: #2B2B2B;
  --ink-soft: #6E6C63;
  --ink-faint: #8A887F;
  --primary: #1F6F62;
  --primary-dark: #18564C;
  --primary-soft: #E4EFEC;
  --accent: #D97742;
  --accent-soft: #F9EDE4;
  --line: #E3E0D8;
  --line-dark: #CFCCC3;
  --radius: 8px;
  --radius-sm: 6px;
  --container: 1200px;
  --narrow: 880px;
  --font-stack: "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Noto Sans CJK SC", sans-serif;
  --shadow-card: 0 1px 3px rgba(43, 43, 43, 0.06);
  --shadow-hover: 0 6px 18px rgba(43, 43, 43, 0.08);
}

*,
*::before,
*::after {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

html {
  font-size: 16px;
  scroll-behavior: smooth;
}

body {
  font-family: var(--font-stack);
  font-size: 16px;
  line-height: 1.8;
  color: var(--ink);
  background-color: var(--bg-paper);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

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

a {
  color: var(--primary);
  text-decoration: none;
  transition: color 0.2s ease;
}

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

ul,
ol {
  list-style: none;
}

h1,
h2,
h3,
h4 {
  font-weight: 700;
  line-height: 1.4;
  color: var(--ink);
}

h1 {
  font-size: 32px;
}

h2 {
  font-size: 24px;
}

h3 {
  font-size: 18px;
}

p {
  color: var(--ink);
}

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

/* ============================================================
   layout - header
   ============================================================ */
.site-header {
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--line);
  position: sticky;
  top: 0;
  z-index: 100;
}

.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0 24px;
  height: 68px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 24px;
}

.brand-link {
  display: inline-flex;
  align-items: center;
  flex-shrink: 0;
}

.brand-text {
  font-size: 22px;
  font-weight: 700;
  color: var(--primary);
  letter-spacing: 0.5px;
}

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

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

.nav-list li {
  position: relative;
}

.nav-list a {
  display: inline-flex;
  align-items: center;
  height: 44px;
  padding: 0 14px;
  font-size: 15px;
  color: var(--ink-soft);
  border-radius: var(--radius-sm);
  transition: color 0.2s ease, background-color 0.2s ease;
}

.nav-list a:hover {
  color: var(--primary);
  background-color: var(--primary-soft);
}

.nav-list a.is-current {
  color: var(--primary);
  font-weight: 600;
  background-color: var(--primary-soft);
}

.nav-toggle {
  display: none;
  width: 44px;
  height: 44px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background-color: var(--bg-card);
  cursor: pointer;
  align-items: center;
  justify-content: center;
  position: relative;
}

.nav-toggle::before,
.nav-toggle::after {
  content: "";
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  width: 20px;
  height: 2px;
  background-color: var(--ink);
  transition: transform 0.2s ease, top 0.2s ease;
}

.nav-toggle::before {
  top: 16px;
  box-shadow: 0 6px 0 var(--ink);
}

.nav-toggle::after {
  top: 28px;
}

.nav-toggle[aria-expanded="true"]::before {
  top: 21px;
  transform: translateX(-50%) rotate(45deg);
  box-shadow: none;
}

.nav-toggle[aria-expanded="true"]::after {
  top: 21px;
  transform: translateX(-50%) rotate(-45deg);
}

/* ============================================================
   layout - main, footer
   ============================================================ */
.site-main {
  min-height: 60vh;
}

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

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

.site-footer {
  background-color: var(--bg-card);
  border-top: 1px solid var(--line);
}

.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 48px 24px 32px;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  gap: 40px;
}

.footer-col h3 {
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 16px;
}

.footer-col ul li {
  margin-bottom: 10px;
}

.footer-col ul a {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.6;
}

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

.footer-bottom {
  border-top: 1px solid var(--line);
  padding: 20px 24px;
  text-align: center;
}

.footer-bottom p {
  font-size: 13px;
  color: var(--ink-faint);
}

.footer-bottom p + p {
  margin-top: 4px;
}

/* ============================================================
   layout - breadcrumb, page header
   ============================================================ */
.breadcrumb {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  padding: 20px 0 0;
  font-size: 14px;
}

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

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

.breadcrumb-sep {
  color: var(--ink-faint);
  font-size: 13px;
}

.breadcrumb-current {
  color: var(--ink);
  font-weight: 500;
}

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

.page-title {
  font-size: 32px;
  line-height: 1.3;
  margin-bottom: 12px;
}

.page-description {
  font-size: 16px;
  color: var(--ink-soft);
  max-width: var(--narrow);
}

/* ============================================================
   layout - section inner
   ============================================================ */
.section-inner {
  max-width: var(--container);
  margin: 0 auto;
}

.section-inner.narrow {
  max-width: var(--narrow);
}

.narrow-section {
  max-width: var(--narrow);
  margin: 0 auto;
}

/* ============================================================
   components - hero
   ============================================================ */
.hero-section {
  display: grid;
  grid-template-columns: 1.1fr 0.9fr;
  gap: 48px;
  align-items: center;
  padding: 56px 0 48px;
}

.hero-content {
  display: flex;
  flex-direction: column;
  align-items: flex-start;
}

.hero-content h1 {
  font-size: 36px;
  line-height: 1.3;
  margin-bottom: 16px;
  color: var(--ink);
}

.hero-slogan {
  font-size: 18px;
  font-weight: 600;
  color: var(--primary);
  margin-bottom: 12px;
}

.hero-intro {
  font-size: 16px;
  color: var(--ink-soft);
  margin-bottom: 28px;
  max-width: 520px;
}

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

.action-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  background-color: var(--primary);
  color: #FFFFFF;
  transition: background-color 0.2s ease;
}

.action-link:hover {
  background-color: var(--primary-dark);
  color: #FFFFFF;
}

.hero-figure {
  border-radius: var(--radius);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  background-color: var(--bg-soft);
}

.hero-figure img {
  width: 100%;
  height: 340px;
  object-fit: cover;
}

/* ============================================================
   components - summary card
   ============================================================ */
.summary-section {
  padding: 24px 0 48px;
}

.summary-card {
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  box-shadow: var(--shadow-card);
  padding: 32px 36px;
}

.summary-card h2 {
  font-size: 22px;
  margin-bottom: 16px;
}

.summary-card > p {
  color: var(--ink-soft);
  margin-bottom: 24px;
}

.summary-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 16px 32px;
}

.summary-list li {
  padding: 12px 0;
  border-top: 1px solid var(--line);
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.6;
}

.summary-list li strong {
  display: block;
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
  margin-bottom: 2px;
}

/* ============================================================
   components - section note
   ============================================================ */
.section-note {
  font-size: 15px;
  color: var(--ink-soft);
  margin-top: 8px;
  margin-bottom: 24px;
}

/* ============================================================
   components - topics wall (home)
   ============================================================ */
.topics-wall {
  padding: 48px 0;
}

.topics-wall > h2 {
  margin-bottom: 8px;
}

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

.topic-card {
  display: block;
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.topic-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.topic-card figure {
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background-color: var(--bg-soft);
}

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

.topic-card h3 {
  font-size: 16px;
  padding: 14px 16px 4px;
}

.topic-card p {
  font-size: 14px;
  color: var(--ink-soft);
  padding: 0 16px 16px;
  line-height: 1.6;
}

/* ============================================================
   components - process steps
   ============================================================ */
.process-section {
  padding: 48px 0;
}

.process-section > h2 {
  margin-bottom: 8px;
}

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

.step-item {
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 24px;
  position: relative;
}

.step-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: var(--primary-soft);
  color: var(--primary);
  font-size: 15px;
  font-weight: 700;
  margin-bottom: 14px;
}

.step-item h3 {
  font-size: 17px;
  margin-bottom: 8px;
}

.step-item p {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 14px;
  line-height: 1.7;
}

.step-item a {
  font-size: 14px;
  font-weight: 500;
}

/* ============================================================
   components - two col section
   ============================================================ */
.two-col-section {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 32px;
  padding: 48px 0;
}

.col-left,
.col-right {
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 32px;
}

.col-left h2,
.col-right h2 {
  font-size: 20px;
  margin-bottom: 16px;
}

.update-digest li {
  padding: 12px 0;
  border-bottom: 1px solid var(--line);
  font-size: 15px;
  color: var(--ink-soft);
  line-height: 1.6;
}

.update-digest li:last-child {
  border-bottom: none;
}

.col-right p {
  font-size: 15px;
  color: var(--ink-soft);
  margin-bottom: 20px;
}

.text-link {
  display: inline-flex;
  align-items: center;
  font-size: 15px;
  font-weight: 500;
  color: var(--primary);
}

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

/* ============================================================
   components - boundary section
   ============================================================ */
.boundary-section {
  background-color: var(--primary-soft);
  border-radius: var(--radius);
  padding: 32px 36px;
  margin: 48px 0 0;
}

.boundary-section h2 {
  font-size: 20px;
  margin-bottom: 12px;
}

.boundary-section p {
  font-size: 15px;
  color: var(--ink);
  margin-bottom: 12px;
  max-width: 720px;
}

.boundary-section .action-link {
  margin-top: 8px;
}

/* ============================================================
   components - related links (home)
   ============================================================ */
.related-links {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 12px;
  padding: 24px 0;
  margin-top: 24px;
  border-top: 1px solid var(--line);
}

.related-links-label {
  font-size: 15px;
  font-weight: 600;
  color: var(--ink);
  margin-right: 8px;
}

.related-links-item {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 16px;
  font-size: 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  color: var(--primary);
  background-color: var(--bg-card);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

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

/* ============================================================
   components - category grid (topics page)
   ============================================================ */
.topics-summary {
  padding-bottom: 40px;
}

.topics-summary h2 {
  margin-bottom: 16px;
}

.topics-summary p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.category-grid-section {
  padding-bottom: 48px;
}

.category-grid-section > h2 {
  margin-bottom: 8px;
}

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

.category-card {
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  overflow: hidden;
  transition: transform 0.2s ease, box-shadow 0.2s ease;
}

.category-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-hover);
}

.category-card a {
  display: block;
  color: inherit;
}

.card-figure {
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  background-color: var(--bg-soft);
}

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

.category-card h3 {
  font-size: 17px;
  padding: 16px 18px 4px;
}

.category-card p {
  font-size: 14px;
  color: var(--ink-soft);
  padding: 0 18px 18px;
  line-height: 1.6;
}

.category-rule {
  padding-bottom: 40px;
}

.category-rule h2 {
  margin-bottom: 16px;
}

.category-rule p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

/* ============================================================
   components - link list
   ============================================================ */
.link-list {
  display: flex;
  flex-direction: column;
  gap: 12px;
}

.link-list li a {
  display: inline-flex;
  align-items: center;
  font-size: 15px;
  font-weight: 500;
  color: var(--primary);
}

.link-list li a:hover {
  color: var(--primary-dark);
}

/* ============================================================
   components - rank list (ranking page)
   ============================================================ */
.rank-rule {
  padding-bottom: 40px;
}

.rank-rule h2 {
  margin-bottom: 16px;
}

.rank-rule p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

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

.content-media-inline {
  max-width: var(--narrow);
  margin: 32px auto;
}

.content-media img {
  width: 100%;
  height: 260px;
  object-fit: cover;
  border-radius: var(--radius);
}

.content-media figcaption {
  font-size: 14px;
  color: var(--ink-faint);
  margin-top: 10px;
  text-align: center;
}

.rank-list-section {
  padding-bottom: 40px;
}

.rank-list-section .section-inner.narrow .rank-list {
  max-width: var(--narrow);
}

.rank-list {
  display: flex;
  flex-direction: column;
  counter-reset: rank;
}

.rank-item {
  display: flex;
  gap: 20px;
  padding: 20px 0;
  border-bottom: 1px solid var(--line);
}

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

.rank-num {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: 50%;
  background-color: var(--primary-soft);
  color: var(--primary);
  font-size: 15px;
  font-weight: 700;
  flex-shrink: 0;
  margin-top: 2px;
}

.rank-content {
  flex: 1;
}

.rank-content h3 {
  font-size: 17px;
  margin-bottom: 6px;
}

.rank-content p {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 8px;
  line-height: 1.7;
}

.rank-content a {
  font-size: 14px;
  font-weight: 500;
}

.rank-footnote {
  padding-bottom: 40px;
}

.rank-footnote h2 {
  margin-bottom: 16px;
}

.rank-footnote p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.related-links-group {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.related-links-group a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 18px;
  font-size: 15px;
  font-weight: 500;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background-color: var(--bg-card);
  color: var(--primary);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

.related-links-group a:hover {
  border-color: var(--primary);
  background-color: var(--primary-soft);
}

/* ============================================================
   components - update entries (updates page)
   ============================================================ */
.update-summary {
  padding-bottom: 40px;
}

.update-summary h2 {
  margin-bottom: 16px;
}

.update-summary p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.update-entries {
  padding-bottom: 48px;
}

.update-entries > .section-inner > h2 {
  margin-bottom: 24px;
}

.entry-list {
  display: flex;
  flex-direction: column;
  gap: 24px;
}

.entry-item {
  display: grid;
  grid-template-columns: 220px 1fr;
  gap: 24px;
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 20px;
  align-items: start;
}

.entry-media {
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  border-radius: var(--radius-sm);
  background-color: var(--bg-soft);
}

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

.entry-body h3 {
  font-size: 17px;
  margin-bottom: 8px;
}

.entry-body p {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 8px;
  line-height: 1.7;
}

.update-rule {
  padding-bottom: 40px;
}

.update-rule > .section-inner > h2 {
  margin-bottom: 24px;
}

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

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

.rule-item h3 {
  font-size: 16px;
  margin-bottom: 8px;
}

.rule-item p {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.7;
}

/* ============================================================
   components - guide steps (guide page)
   ============================================================ */
.anchor-nav {
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px 20px;
  margin-bottom: 40px;
}

.anchor-nav ul {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.anchor-nav li a {
  display: inline-flex;
  align-items: center;
  min-height: 40px;
  padding: 0 16px;
  font-size: 14px;
  border-radius: var(--radius-sm);
  color: var(--ink-soft);
  transition: background-color 0.2s ease, color 0.2s ease;
}

.anchor-nav li a:hover {
  background-color: var(--primary-soft);
  color: var(--primary);
}

.guide-step {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 40px;
  align-items: center;
  padding: 40px 0;
  border-bottom: 1px solid var(--line);
}

.guide-step:last-of-type {
  border-bottom: none;
}

.step-text h2 {
  font-size: 22px;
  margin-bottom: 16px;
}

.step-text p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.step-text a {
  font-weight: 500;
}

.step-media {
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--bg-soft);
}

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

.step-media figcaption {
  font-size: 14px;
  color: var(--ink-faint);
  padding: 10px 14px;
  background-color: var(--bg-card);
}

/* ============================================================
   components - faq
   ============================================================ */
.faq-section {
  padding: 48px 0 40px;
  max-width: var(--narrow);
  margin: 0 auto;
}

.faq-section h2 {
  margin-bottom: 24px;
}

.faq-item {
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background-color: var(--bg-card);
  margin-bottom: 12px;
}

.faq-item summary {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 18px 20px;
  font-size: 15px;
  font-weight: 600;
  cursor: pointer;
  color: var(--ink);
  list-style: none;
}

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

.faq-item summary::after {
  content: "";
  width: 10px;
  height: 10px;
  border-right: 2px solid var(--ink-soft);
  border-bottom: 2px solid var(--ink-soft);
  transform: rotate(45deg);
  transition: transform 0.2s ease;
  margin-left: 12px;
  flex-shrink: 0;
}

.faq-item[open] summary::after {
  transform: rotate(-135deg);
}

.faq-item p {
  padding: 0 20px 18px;
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.8;
}

/* ============================================================
   components - legal (copyright page)
   ============================================================ */
.legal-summary {
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 32px;
  margin-bottom: 40px;
}

.legal-summary h2 {
  font-size: 20px;
  margin-bottom: 12px;
}

.legal-summary > p {
  color: var(--ink-soft);
  margin-bottom: 16px;
}

.legal-summary .summary-list {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px 24px;
}

.legal-summary .summary-list li {
  font-size: 14px;
  color: var(--ink-soft);
  line-height: 1.7;
}

.legal-summary .summary-list li a {
  font-weight: 500;
}

.legal-section {
  max-width: var(--narrow);
  padding-bottom: 40px;
}

.legal-section h2 {
  font-size: 20px;
  margin-bottom: 16px;
  padding-bottom: 8px;
  border-bottom: 1px solid var(--line);
}

.legal-section p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.citation-figure {
  margin: 20px 0;
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--bg-soft);
}

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

.citation-figure figcaption {
  font-size: 14px;
  color: var(--ink-faint);
  padding: 10px 14px;
  background-color: var(--bg-card);
}

/* ============================================================
   components - share copy
   ============================================================ */
.share-copy {
  max-width: var(--narrow);
  margin: 0 auto 40px;
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 28px 32px;
}

.share-copy h2 {
  font-size: 20px;
  margin-bottom: 12px;
}

.share-copy p {
  font-size: 15px;
  color: var(--ink-soft);
  margin-bottom: 16px;
}

.copy-link-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 20px;
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  border: none;
  background-color: var(--primary);
  color: #FFFFFF;
  cursor: pointer;
  transition: background-color 0.2s ease;
}

.copy-link-btn:hover {
  background-color: var(--primary-dark);
}

.copy-fallback {
  margin-top: 16px;
  padding: 14px 16px;
  background-color: var(--bg-soft);
  border-radius: var(--radius-sm);
  font-size: 14px;
  word-break: break-all;
  user-select: all;
}

/* ============================================================
   components - about page
   ============================================================ */
.about-intro {
  padding-bottom: 40px;
}

.about-intro h2 {
  margin-bottom: 16px;
}

.about-intro p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.column-index {
  padding-bottom: 48px;
}

.column-index > .section-inner > h2 {
  margin-bottom: 8px;
}

.section-lead {
  color: var(--ink-soft);
  margin-bottom: 24px;
}

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

.column-item {
  display: grid;
  grid-template-columns: 160px 1fr;
  gap: 20px;
  background-color: var(--bg-card);
  border: 1px solid var(--line);
  border-radius: var(--radius);
  padding: 16px;
  align-items: start;
}

.column-media {
  width: 100%;
  aspect-ratio: 4 / 3;
  overflow: hidden;
  border-radius: var(--radius-sm);
  background-color: var(--bg-soft);
}

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

.column-body h3 {
  font-size: 16px;
  margin-bottom: 6px;
}

.column-body p {
  font-size: 14px;
  color: var(--ink-soft);
  margin-bottom: 8px;
  line-height: 1.7;
}

.column-body a {
  font-size: 14px;
  font-weight: 500;
}

.scope-note {
  padding-bottom: 40px;
}

.scope-note h2 {
  margin-bottom: 16px;
}

.scope-note > .section-inner > p {
  color: var(--ink-soft);
  margin-bottom: 12px;
}

.scope-list {
  margin: 16px 0;
  padding-left: 20px;
  list-style: disc;
}

.scope-list li {
  font-size: 15px;
  color: var(--ink-soft);
  margin-bottom: 8px;
  line-height: 1.7;
}

.related-list {
  display: flex;
  flex-wrap: wrap;
  gap: 12px;
}

.related-list a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 0 18px;
  font-size: 15px;
  font-weight: 500;
  border: 1px solid var(--line);
  border-radius: var(--radius-sm);
  background-color: var(--bg-card);
  color: var(--primary);
  transition: border-color 0.2s ease, background-color 0.2s ease;
}

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

/* ============================================================
   components - 404
   ============================================================ */
.error-main {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 60vh;
  padding: 48px 24px;
}

.error-section {
  text-align: center;
  max-width: 520px;
}

.error-code {
  font-size: 72px;
  font-weight: 700;
  color: var(--primary);
  line-height: 1;
  margin-bottom: 16px;
}

.error-section h1 {
  font-size: 24px;
  margin-bottom: 12px;
}

.error-desc {
  font-size: 15px;
  color: var(--ink-soft);
  margin-bottom: 24px;
}

.error-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-height: 44px;
  padding: 0 24px;
  font-size: 15px;
  font-weight: 500;
  border-radius: var(--radius-sm);
  background-color: var(--primary);
  color: #FFFFFF;
}

.error-link:hover {
  background-color: var(--primary-dark);
  color: #FFFFFF;
}

/* ============================================================
   pages - specific adjustments
   ============================================================ */
/* page-topics: category grid uses 3 columns */
.page-topics .category-grid {
  grid-template-columns: repeat(3, 1fr);
}

/* page-ranking: rank list naturally narrow */
.page-ranking .rank-list {
  max-width: var(--narrow);
}

/* page-guide: alternate step layout for odd steps */
.page-guide .guide-step:nth-child(even) {
  direction: rtl;
}

.page-guide .guide-step:nth-child(even) > * {
  direction: ltr;
}

/* ============================================================
   responsive
   ============================================================ */
@media (max-width: 992px) {
  .header-inner {
    height: 60px;
  }

  .nav-toggle {
    display: inline-flex;
  }

  .nav-list {
    display: none;
    position: absolute;
    top: 60px;
    left: 0;
    right: 0;
    background-color: var(--bg-card);
    border-bottom: 1px solid var(--line);
    padding: 8px 24px 16px;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    box-shadow: 0 8px 16px rgba(43, 43, 43, 0.06);
  }

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

  .nav-list li {
    width: 100%;
  }

  .nav-list a {
    width: 100%;
    height: 44px;
    padding: 0 12px;
    font-size: 16px;
  }

  .hero-section {
    grid-template-columns: 1fr;
    gap: 32px;
    padding: 40px 0 32px;
  }

  .hero-content {
    order: 1;
  }

  .hero-figure {
    order: 2;
  }

  .hero-figure img {
    height: 280px;
  }

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

  .process-steps {
    grid-template-columns: repeat(2, 1fr);
  }

  .two-col-section {
    grid-template-columns: 1fr;
  }

  .footer-inner {
    grid-template-columns: repeat(2, 1fr);
    gap: 32px;
  }

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

  .rule-list {
    grid-template-columns: repeat(2, 1fr);
  }

  .guide-step {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .page-guide .guide-step:nth-child(even) {
    direction: ltr;
  }

  .step-media img {
    height: 220px;
  }

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

  .entry-media {
    max-width: 320px;
  }

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

  .column-item {
    grid-template-columns: 140px 1fr;
  }
}

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

  .brand-text {
    font-size: 20px;
  }

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

  .breadcrumb {
    padding-top: 16px;
  }

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

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

  .hero-content h1 {
    font-size: 28px;
  }

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

  .hero-actions {
    flex-direction: column;
    align-items: stretch;
    width: 100%;
  }

  .action-link {
    width: 100%;
  }

  .hero-figure img {
    height: 220px;
  }

  .summary-card {
    padding: 24px 20px;
  }

  .summary-list {
    grid-template-columns: 1fr;
    gap: 0;
  }

  .topics-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 16px;
  }

  .topic-card h3 {
    font-size: 15px;
    padding: 12px 14px 4px;
  }

  .topic-card p {
    font-size: 13px;
    padding: 0 14px 14px;
  }

  .process-steps {
    grid-template-columns: 1fr;
  }

  .boundary-section {
    padding: 24px 20px;
  }

  .footer-inner {
    grid-template-columns: 1fr;
    gap: 24px;
    padding: 32px 16px 24px;
  }

  .footer-col h3 {
    margin-bottom: 12px;
  }

  .category-grid {
    grid-template-columns: 1fr;
    gap: 16px;
  }

  .rank-item {
    gap: 14px;
  }

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

  .anchor-nav ul {
    flex-direction: column;
    gap: 4px;
  }

  .anchor-nav li a {
    width: 100%;
  }

  .faq-section {
    padding: 32px 0 32px;
  }

  .legal-summary {
    padding: 20px;
  }

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

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

  .column-media {
    max-width: 240px;
  }

  .entry-media {
    max-width: 100%;
  }

  .content-media img {
    height: 200px;
  }

  .step-media img {
    height: 200px;
  }

  .citation-figure img {
    height: 200px;
  }

  .error-code {
    font-size: 56px;
  }
}

@media (max-width: 480px) {
  .topics-grid {
    grid-template-columns: 1fr;
  }

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

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

  .hero-actions {
    flex-direction: column;
  }

  .action-link {
    width: 100%;
    text-align: center;
  }

  .related-links {
    align-items: stretch;
    flex-direction: column;
  }

  .related-links-item {
    width: 100%;
    justify-content: center;
  }

  .related-links-group {
    flex-direction: column;
    width: 100%;
  }

  .related-links-group a {
    width: 100%;
    justify-content: center;
  }

  .related-list {
    flex-direction: column;
    width: 100%;
  }

  .related-list a {
    width: 100%;
    justify-content: center;
  }

  .share-copy {
    padding: 20px;
  }

  .copy-link-btn {
    width: 100%;
  }
}