:root {
  --bg-page: #f7f9fa;
  --bg-elevated: #ffffff;
  --bg-mono: #eef3f4;
  --text-main: #1c2b33;
  --text-sub: #5b6b73;
  --accent: #1f7a8c;
  --accent-dark: #17606f;
  --status: #2f9e6b;
  --border: #dbe3e6;
  --border-strong: #c3d0d4;
  --font-sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", "Helvetica Neue", Arial, sans-serif;
  --font-mono: ui-monospace, SFMono-Regular, "SF Mono", Menlo, Consolas, "Liberation Mono", "Courier New", monospace;
  --radius: 6px;
  --radius-sm: 4px;
  --shadow-soft: 0 1px 2px rgba(28, 43, 51, 0.05);
  --container: 1120px;
  --body-max: 760px;
}

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

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

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

body {
  margin: 0;
  padding: 0;
  background-color: var(--bg-page);
  color: var(--text-main);
  font-family: var(--font-sans);
  font-size: 1rem;
  line-height: 1.75;
}

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

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

a:hover,
a:focus-visible {
  color: var(--accent-dark);
  text-decoration: underline;
}

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

h1, h2, h3, h4 {
  color: var(--text-main);
  line-height: 1.35;
  margin: 0 0 0.6em;
  font-weight: 700;
}

h1 { font-size: 1.9rem; }
h2 { font-size: 1.3rem; }
h3 { font-size: 1.05rem; }

p {
  margin: 0 0 1em;
}

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

li {
  margin-bottom: 0.35em;
}

code, pre, kbd, samp {
  font-family: var(--font-mono);
  font-size: 0.92rem;
}

pre {
  margin: 0 0 1em;
  overflow-x: auto;
}

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

th, td {
  text-align: left;
  vertical-align: top;
}

button {
  font-family: inherit;
  font-size: 1rem;
  cursor: pointer;
}

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

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 100;
  padding: 0.6em 1em;
  background: var(--accent);
  color: #fff;
  border-radius: 0 0 var(--radius-sm) 0;
}

.skip-link:focus {
  left: 0;
  color: #fff;
  text-decoration: none;
}

/* ============================================================
   layout · shell (header / nav / main / footer)
   ============================================================ */

.site-body {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 40;
  background-color: var(--bg-elevated);
  border-bottom: 1px solid var(--border);
}

.header-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 0.75rem 1.25rem;
  display: flex;
  align-items: center;
  gap: 1.25rem;
}

.brand {
  font-size: 1.05rem;
  font-weight: 700;
  color: var(--text-main);
  letter-spacing: 0;
  white-space: nowrap;
  flex-shrink: 0;
}

.brand:hover,
.brand:focus-visible {
  color: var(--accent);
  text-decoration: none;
}

.nav-toggle {
  display: none;
  background: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  width: 44px;
  height: 44px;
  padding: 0;
  color: var(--text-main);
  flex-shrink: 0;
}

.nav-toggle::before {
  content: "";
  display: block;
  width: 18px;
  height: 2px;
  margin: 0 auto;
  background: currentColor;
  box-shadow: 0 -6px 0 currentColor, 0 6px 0 currentColor;
}

.site-nav {
  flex: 1 1 auto;
  min-width: 0;
}

.nav-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: flex;
  flex-wrap: wrap;
  gap: 0.25rem 1.1rem;
  align-items: center;
}

.nav-list li {
  margin: 0;
}

.nav-list a {
  display: inline-block;
  padding: 0.35rem 0.1rem;
  color: var(--text-sub);
  font-size: 0.95rem;
  border-bottom: 2px solid transparent;
}

.nav-list a:hover,
.nav-list a:focus-visible {
  color: var(--accent);
  text-decoration: none;
}

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

.header-tools {
  display: flex;
  align-items: center;
  gap: 0.75rem;
  flex-shrink: 0;
}

.tool-link {
  font-size: 0.9rem;
  color: var(--text-sub);
  padding: 0.4rem 0.75rem;
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  white-space: nowrap;
  display: inline-block;
  min-height: 34px;
  line-height: 1.4;
}

.tool-link:hover,
.tool-link:focus-visible {
  color: var(--accent);
  border-color: var(--accent);
  text-decoration: none;
}

.tool-link.back-top {
  border-color: transparent;
  padding: 0.4rem 0.5rem;
}

.site-main {
  flex: 1 0 auto;
  width: 100%;
  max-width: var(--container);
  margin: 0 auto;
  padding: 1.75rem 1.25rem 3rem;
}

.inner-main {
  padding-top: 1.5rem;
}

.breadcrumb {
  font-size: 0.88rem;
  color: var(--text-sub);
  margin-bottom: 1rem;
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 0.4rem;
}

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

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

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

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

.page-header {
  margin-bottom: 1.75rem;
}

.page-title {
  font-size: 1.9rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 0 0 0.5rem;
  line-height: 1.3;
}

.page-description {
  color: var(--text-sub);
  max-width: var(--body-max);
  margin: 0;
}

.site-footer {
  background-color: var(--bg-elevated);
  border-top: 1px solid var(--border);
  margin-top: auto;
}

.footer-inner {
  max-width: var(--container);
  margin: 0 auto;
  padding: 2.25rem 1.25rem 1.25rem;
  display: grid;
  grid-template-columns: 1.6fr 1fr 1fr 1fr;
  gap: 1.75rem 2rem;
}

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

.footer-name {
  font-weight: 700;
  color: var(--text-main);
  margin: 0 0 0.4rem;
}

.footer-desc {
  color: var(--text-sub);
  font-size: 0.9rem;
  margin: 0;
  max-width: 30ch;
}

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

.footer-title {
  font-size: 0.9rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 0 0 0.6rem;
  text-transform: none;
}

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

.footer-group li {
  margin-bottom: 0.4rem;
}

.footer-group a {
  color: var(--text-sub);
  font-size: 0.9rem;
}

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

.footer-bottom {
  grid-column: 1 / -1;
  border-top: 1px solid var(--border);
  padding-top: 1rem;
  margin-top: 0.5rem;
  display: flex;
  flex-wrap: wrap;
  justify-content: space-between;
  align-items: center;
  gap: 0.5rem;
}

.footer-copy {
  margin: 0;
  font-size: 0.85rem;
  color: var(--text-sub);
}

.footer-top {
  font-size: 0.85rem;
  color: var(--text-sub);
}

.footer-top:hover,
.footer-top:focus-visible {
  color: var(--accent);
}

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

.btn {
  display: inline-block;
  padding: 0.6rem 1.15rem;
  border-radius: var(--radius-sm);
  font-size: 0.95rem;
  font-weight: 600;
  border: 1px solid transparent;
  min-height: 44px;
  line-height: 1.5;
  text-align: center;
}

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

.btn-primary:hover,
.btn-primary:focus-visible {
  background-color: var(--accent-dark);
  border-color: var(--accent-dark);
  color: #fff;
  text-decoration: none;
}

.btn-ghost {
  background-color: transparent;
  color: var(--accent);
  border-color: var(--border-strong);
}

.btn-ghost:hover,
.btn-ghost:focus-visible {
  border-color: var(--accent);
  color: var(--accent-dark);
  text-decoration: none;
}

.inline-cta {
  font-weight: 600;
  display: inline-block;
}

.inline-cta::after {
  content: " →";
  font-weight: 400;
}

.card-link,
.link-more {
  display: inline-block;
  font-size: 0.92rem;
  font-weight: 600;
  margin-top: 0.35rem;
}

.card-link::after,
.link-more::after {
  content: " →";
  font-weight: 400;
}

.section-head {
  margin-bottom: 1.1rem;
}

.section-head h2 {
  margin-bottom: 0.35rem;
}

.section-head p {
  color: var(--text-sub);
  margin: 0;
  max-width: var(--body-max);
}

.section-foot {
  margin: 1rem 0 0;
  font-size: 0.92rem;
}

.section-note {
  margin: 1rem 0 0;
  font-size: 0.92rem;
  color: var(--text-sub);
}

.section-intro {
  color: var(--text-sub);
  max-width: var(--body-max);
}

.subsection-title {
  font-size: 1rem;
  margin: 0 0 0.5rem;
}

.data-table {
  width: 100%;
  border: 1px solid var(--border);
  background-color: var(--bg-elevated);
  font-size: 0.95rem;
}

.data-table caption {
  caption-side: top;
  text-align: left;
  padding: 0.5rem 0.75rem;
  font-size: 0.85rem;
  color: var(--text-sub);
}

.data-table th,
.data-table td {
  padding: 0.7rem 0.85rem;
  border-bottom: 1px solid var(--border);
}

.data-table thead th {
  background-color: var(--bg-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--text-sub);
  white-space: nowrap;
}

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

.data-table tbody th {
  font-weight: 600;
}

.data-table tbody tr:hover {
  background-color: #f3f7f8;
}

.table-wrap,
.table-scroll,
.mapping-table-wrap {
  overflow-x: auto;
  -webkit-overflow-scrolling: touch;
}

.table-scroll .data-table,
.mapping-table-wrap .mapping-table {
  min-width: 640px;
}

/* ============================================================
   pages · home
   ============================================================ */

.home-main {
  padding-top: 1.75rem;
}

.hero-section {
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(0, 420px);
  gap: 2rem;
  align-items: center;
  padding-bottom: 2rem;
  border-bottom: 1px solid var(--border);
  margin-bottom: 2rem;
}

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

.hero-eyebrow {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  background-color: var(--bg-mono);
  display: inline-block;
  padding: 0.2rem 0.6rem;
  border-radius: var(--radius-sm);
  margin: 0 0 0.9rem;
}

.hero-title {
  font-size: 1.9rem;
  margin: 0 0 0.75rem;
  line-height: 1.3;
}

.hero-lead {
  color: var(--text-sub);
  max-width: 46ch;
  margin: 0 0 1.25rem;
}

.hero-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
}

.hero-media {
  margin: 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--bg-elevated);
}

.hero-media img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 10;
  object-fit: cover;
}

.hero-media figcaption {
  padding: 0.6rem 0.85rem;
  font-size: 0.85rem;
  color: var(--text-sub);
  border-top: 1px solid var(--border);
}

.direction-summary {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-left: 3px solid var(--accent);
  border-radius: var(--radius);
  padding: 1.25rem 1.4rem;
  margin-bottom: 2.5rem;
}

.direction-summary h2 {
  margin-bottom: 0.5rem;
}

.direction-summary p {
  color: var(--text-sub);
  margin-bottom: 0.6rem;
  max-width: var(--body-max);
}

.direction-summary p:last-of-type {
  margin-bottom: 0.9rem;
}

.section-block {
  margin-bottom: 2.75rem;
}

.channel-table th[scope="row"] {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  color: var(--text-main);
  white-space: nowrap;
}

.playlist-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.1rem;
}

.playlist-card {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem 1.15rem;
  display: flex;
  flex-direction: column;
  min-width: 0;
  transition: border-color 0.15s ease, box-shadow 0.15s ease;
}

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

.playlist-name {
  font-size: 1.05rem;
  margin: 0 0 0.5rem;
}

.playlist-scope {
  color: var(--text-sub);
  font-size: 0.92rem;
  margin: 0 0 0.5rem;
}

.playlist-org {
  color: var(--text-sub);
  font-size: 0.92rem;
  margin: 0 0 0.6rem;
  flex: 1 1 auto;
}

.section-media {
  margin: 1.5rem 0 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--bg-elevated);
}

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

.section-media figcaption {
  padding: 0.6rem 0.85rem;
  font-size: 0.85rem;
  color: var(--text-sub);
  border-top: 1px solid var(--border);
}

.field-table th[scope="row"] {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  white-space: nowrap;
}

.boundary-note {
  margin: 1rem 0 0;
  padding: 0.85rem 1rem;
  background-color: var(--bg-mono);
  border-radius: var(--radius-sm);
  font-size: 0.92rem;
  color: var(--text-sub);
}

.path-overview .step-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.1rem;
  counter-reset: step;
}

.step-list .step-item {
  margin: 0;
  padding: 1.1rem 1.15rem;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-width: 0;
}

.step-list .step-index {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--status);
  background-color: var(--bg-mono);
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  margin-bottom: 0.5rem;
}

.step-list .step-name {
  font-size: 1.02rem;
  margin: 0 0 0.45rem;
}

.step-list .step-action,
.step-list .step-result {
  font-size: 0.92rem;
  color: var(--text-sub);
  margin: 0 0 0.4rem;
}

.step-list .step-result {
  margin-bottom: 0;
}

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

.changelog-item {
  margin: 0;
  padding: 0.9rem 0.25rem;
  border-bottom: 1px solid var(--border);
  display: grid;
  grid-template-columns: 7.5rem 6rem minmax(0, 1fr) auto;
  gap: 0.75rem 1rem;
  align-items: baseline;
}

.changelog-item:hover {
  background-color: #f3f7f8;
}

.changelog-date {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--text-sub);
}

.changelog-type {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--status);
  background-color: var(--bg-mono);
  border-radius: var(--radius-sm);
  padding: 0.1rem 0.5rem;
  justify-self: start;
  white-space: nowrap;
}

.changelog-desc {
  margin: 0;
  font-size: 0.95rem;
  min-width: 0;
}

.changelog-link {
  font-size: 0.9rem;
  white-space: nowrap;
}

.feedback-note {
  margin: 1.25rem 0 0;
  font-size: 0.92rem;
  color: var(--text-sub);
}

/* ============================================================
   pages · inner shared (two-column shell)
   ============================================================ */

.page-layout {
  display: grid;
  grid-template-columns: 240px minmax(0, 1fr);
  gap: 2rem;
  align-items: start;
}

.page-layout.sidebar-left {
  grid-template-columns: 240px minmax(0, 1fr);
}

.sidebar-left .page-layout {
  grid-template-columns: 240px minmax(0, 1fr);
}

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

.page-sidebar,
.page-aside {
  position: sticky;
  top: 5rem;
  align-self: start;
  min-width: 0;
}

.sidebar-nav,
.aside-nav,
.sidebar-block,
.aside-block {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1rem 1.1rem;
  margin-bottom: 1.1rem;
}

.sidebar-title,
.aside-title {
  font-size: 0.88rem;
  font-weight: 700;
  color: var(--text-main);
  margin: 0 0 0.6rem;
}

.sidebar-list,
.aside-list,
.anchor-list,
.aside-steps {
  list-style: none;
  margin: 0;
  padding: 0;
}

.sidebar-list li,
.aside-list li,
.anchor-list li,
.aside-steps li {
  margin: 0 0 0.3rem;
}

.sidebar-list a,
.aside-list a,
.anchor-list a,
.aside-steps a {
  display: block;
  font-size: 0.9rem;
  color: var(--text-sub);
  padding: 0.3rem 0.4rem;
  border-left: 2px solid transparent;
  border-radius: 0 var(--radius-sm) var(--radius-sm) 0;
}

.sidebar-list a:hover,
.aside-list a:hover,
.anchor-list a:hover,
.aside-steps a:hover,
.sidebar-list a:focus-visible,
.aside-list a:focus-visible,
.anchor-list a:focus-visible,
.aside-steps a:focus-visible {
  color: var(--accent);
  background-color: var(--bg-mono);
  text-decoration: none;
}

.sidebar-list a.is-current {
  color: var(--accent);
  border-left-color: var(--accent);
  font-weight: 600;
  background-color: var(--bg-mono);
}

.aside-toggle {
  display: none;
  width: 100%;
  text-align: left;
  padding: 0.7rem 1rem;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border-strong);
  border-radius: var(--radius-sm);
  color: var(--text-main);
  font-weight: 600;
  min-height: 44px;
}

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

.content-section {
  margin-bottom: 2.5rem;
}

.content-section h2 {
  margin-bottom: 0.5rem;
}

.page-figure,
.content-figure,
.media-figure,
.path-figure {
  margin: 1.25rem 0;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  overflow: hidden;
  background-color: var(--bg-elevated);
}

.page-figure img,
.content-figure img,
.media-figure img,
.path-figure img {
  width: 100%;
  height: auto;
  aspect-ratio: 16 / 9;
  object-fit: cover;
}

.page-figure figcaption,
.content-figure figcaption,
.media-figure figcaption,
.path-figure figcaption {
  padding: 0.6rem 0.85rem;
  font-size: 0.85rem;
  color: var(--text-sub);
  border-top: 1px solid var(--border);
}

.field-label {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  background-color: var(--bg-mono);
  padding: 0.1rem 0.45rem;
  border-radius: var(--radius-sm);
  margin-right: 0.4rem;
}

.next-links {
  border-top: 1px solid var(--border);
  padding-top: 1.5rem;
}

.next-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 0.6rem 1.5rem;
}

.next-list li {
  margin: 0;
  font-size: 0.95rem;
}

/* ============================================================
   pages · channels
   ============================================================ */

.page-channels .channel-block {
  border-top: 1px solid var(--border);
  padding-top: 1.1rem;
  margin-bottom: 1.25rem;
}

.page-channels .channel-name {
  font-size: 1.05rem;
  margin: 0 0 0.4rem;
}

.page-channels .channel-desc {
  color: var(--text-sub);
  margin: 0 0 0.5rem;
}

.page-channels .channel-audience,
.page-channels .channel-range {
  font-size: 0.92rem;
  margin: 0 0 0.35rem;
}

.page-channels .pair-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--border);
}

.page-channels .pair-row {
  display: grid;
  grid-template-columns: minmax(120px, 200px) minmax(0, 1fr);
  gap: 0.75rem 1rem;
  padding: 0.7rem 0.25rem;
  border-bottom: 1px solid var(--border);
  margin: 0;
  font-size: 0.95rem;
}

.page-channels .pair-row:hover {
  background-color: #f3f7f8;
}

.page-channels .pair-key {
  font-weight: 600;
  color: var(--text-main);
}

.page-channels .pair-value {
  color: var(--text-sub);
  min-width: 0;
}

.page-channels .tips-columns {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 1.5rem;
}

.page-channels .tips-column {
  min-width: 0;
}

.page-channels .tips-list {
  margin: 0;
  padding-left: 1.2em;
  color: var(--text-sub);
  font-size: 0.95rem;
}

/* ============================================================
   pages · playlists
   ============================================================ */

.page-playlists .section {
  margin-bottom: 2.5rem;
}

.page-playlists .playlist-cards {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.1rem;
}

.page-playlists .playlist-card {
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 1.1rem 1.15rem;
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.page-playlists .playlist-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow-soft);
}

.page-playlists .playlist-meta {
  margin: 0 0 0.6rem;
  font-size: 0.9rem;
  flex: 1 1 auto;
}

.page-playlists .playlist-meta dt {
  font-family: var(--font-mono);
  font-size: 0.82rem;
  color: var(--text-sub);
  margin-bottom: 0.15rem;
}

.page-playlists .playlist-meta dd {
  margin: 0 0 0.55rem;
  color: var(--text-main);
}

.page-playlists .playlist-meta dd:last-child {
  margin-bottom: 0;
}

.page-playlists .playlist-detail {
  border-top: 1px solid var(--border);
  padding-top: 1.1rem;
  margin-bottom: 1.25rem;
}

.page-playlists .playlist-detail-name {
  font-size: 1.05rem;
  margin: 0 0 0.4rem;
}

.page-playlists .playlist-detail-scope {
  color: var(--text-sub);
  margin: 0 0 0.6rem;
}

.page-playlists .playlist-detail-list {
  margin: 0;
}

.page-playlists .playlist-detail-list dt {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  margin-bottom: 0.15rem;
}

.page-playlists .playlist-detail-list dd {
  margin: 0 0 0.7rem;
  font-size: 0.95rem;
}

.page-playlists .playlist-detail-list dd:last-child {
  margin-bottom: 0;
}

.page-playlists .mapping-table {
  min-width: 520px;
  border: 1px solid var(--border);
  background-color: var(--bg-elevated);
  font-size: 0.95rem;
}

.page-playlists .mapping-table caption {
  caption-side: top;
  text-align: left;
  padding: 0.5rem 0.75rem;
  font-size: 0.85rem;
  color: var(--text-sub);
}

.page-playlists .mapping-table th,
.page-playlists .mapping-table td {
  padding: 0.7rem 0.85rem;
  border-bottom: 1px solid var(--border);
}

.page-playlists .mapping-table thead th {
  background-color: var(--bg-mono);
  font-size: 0.85rem;
  color: var(--text-sub);
}

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

.page-playlists .update-list {
  list-style: none;
  margin: 0;
  padding: 0;
  border-top: 1px solid var(--border);
}

.page-playlists .update-item {
  margin: 0;
  padding: 0.9rem 0.25rem;
  border-bottom: 1px solid var(--border);
}

.page-playlists .update-item:hover {
  background-color: #f3f7f8;
}

.page-playlists .update-date {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--text-sub);
  margin: 0 0 0.25rem;
}

.page-playlists .update-body {
  margin: 0 0 0.25rem;
  font-size: 0.95rem;
}

.page-playlists .update-type {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--status);
  background-color: var(--bg-mono);
  border-radius: var(--radius-sm);
  padding: 0.1rem 0.5rem;
  margin-right: 0.5rem;
}

.page-playlists .update-impact {
  margin: 0;
  font-size: 0.9rem;
  color: var(--text-sub);
}

/* ============================================================
   pages · fields
   ============================================================ */

.page-fields .fields-table th[scope="row"] {
  font-family: var(--font-mono);
  font-size: 0.9rem;
  white-space: nowrap;
}

.page-fields .sample-block {
  border-top: 1px solid var(--border);
  padding-top: 1rem;
  margin-bottom: 1.1rem;
}

.page-fields .sample-block h3 {
  font-family: var(--font-mono);
  font-size: 0.95rem;
  margin: 0 0 0.5rem;
}

.page-fields .code-sample {
  background-color: var(--bg-mono);
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  padding: 0.75rem 0.9rem;
  margin: 0 0 0.5rem;
  font-size: 0.88rem;
  line-height: 1.6;
  color: var(--text-main);
}

.page-fields .sample-block p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--text-sub);
}

.page-fields .rule-list {
  margin: 0 0 1rem;
}

.page-fields .rule-list dt {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--accent);
  margin-bottom: 0.15rem;
}

.page-fields .rule-list dd {
  margin: 0 0 0.8rem;
  font-size: 0.95rem;
}

.page-fields .rule-list dd:last-child {
  margin-bottom: 0;
}

.page-fields .path-table th,
.page-fields .path-table td {
  font-size: 0.95rem;
}

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

.page-guide .path-steps {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.1rem;
}

.page-guide .path-step {
  margin: 0;
  padding: 1.1rem 1.15rem;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-width: 0;
}

.page-guide .path-step .step-index {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--status);
  background-color: var(--bg-mono);
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  margin-bottom: 0.5rem;
}

.page-guide .path-step .step-name {
  font-size: 1.02rem;
  margin: 0 0 0.45rem;
}

.page-guide .path-step .step-goal {
  font-size: 0.92rem;
  color: var(--text-sub);
  margin: 0;
}

.page-guide .step-block {
  border-top: 1px solid var(--border);
  padding-top: 1.1rem;
  margin-bottom: 1.25rem;
}

.page-guide .step-block h3 {
  font-size: 1.05rem;
  margin: 0 0 0.6rem;
}

.page-guide .step-rows {
  margin: 0;
  display: grid;
  grid-template-columns: 6rem minmax(0, 1fr);
  gap: 0.4rem 1rem;
}

.page-guide .step-rows dt {
  font-family: var(--font-mono);
  font-size: 0.85rem;
  color: var(--accent);
  padding-top: 0.1rem;
}

.page-guide .step-rows dd {
  margin: 0;
  font-size: 0.95rem;
}

.page-guide .back-list {
  list-style: none;
  margin: 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.1rem;
}

.page-guide .back-item {
  margin: 0;
  padding: 1rem 1.1rem;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-width: 0;
}

.page-guide .back-item h3 {
  font-size: 1rem;
  margin: 0 0 0.4rem;
}

.page-guide .back-item p {
  margin: 0;
  font-size: 0.92rem;
  color: var(--text-sub);
}

.page-guide .faq-item {
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background-color: var(--bg-elevated);
  margin-bottom: 0.6rem;
  overflow: hidden;
}

.page-guide .faq-item summary {
  cursor: pointer;
  padding: 0.8rem 1rem;
  font-weight: 600;
  font-size: 0.97rem;
  color: var(--text-main);
  list-style: none;
  position: relative;
  padding-right: 2.4rem;
}

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

.page-guide .faq-item summary::after {
  content: "+";
  position: absolute;
  right: 1rem;
  top: 50%;
  transform: translateY(-50%);
  font-family: var(--font-mono);
  color: var(--accent);
  font-size: 1.1rem;
}

.page-guide .faq-item[open] summary::after {
  content: "−";
}

.page-guide .faq-item summary:hover {
  background-color: var(--bg-mono);
}

.page-guide .faq-item p {
  margin: 0;
  padding: 0 1rem 0.9rem;
  font-size: 0.94rem;
  color: var(--text-sub);
}

/* ============================================================
   pages · boundaries
   ============================================================ */

.page-boundaries .def-list {
  margin: 0 0 1rem;
}

.page-boundaries .def-list dt {
  font-weight: 600;
  color: var(--text-main);
  margin-bottom: 0.15rem;
}

.page-boundaries .def-list dd {
  margin: 0 0 0.8rem;
  font-size: 0.95rem;
  color: var(--text-sub);
}

.page-boundaries .def-list dd:last-child {
  margin-bottom: 0;
}

.page-boundaries .plain-list {
  margin: 0 0 1rem;
  padding-left: 1.3em;
}

.page-boundaries .plain-list li {
  margin-bottom: 0.5rem;
  font-size: 0.95rem;
  color: var(--text-sub);
}

.page-boundaries .plain-list strong {
  color: var(--text-main);
}

.page-boundaries .timeline-list {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
  border-top: 1px solid var(--border);
}

.page-boundaries .timeline-item {
  margin: 0;
  padding: 0.9rem 0.25rem;
  border-bottom: 1px solid var(--border);
}

.page-boundaries .timeline-item:hover {
  background-color: #f3f7f8;
}

.page-boundaries .timeline-date {
  font-family: var(--font-mono);
  font-size: 0.88rem;
  color: var(--text-sub);
  margin: 0 0 0.2rem;
}

.page-boundaries .timeline-type {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--status);
  background-color: var(--bg-mono);
  border-radius: var(--radius-sm);
  padding: 0.1rem 0.5rem;
  display: inline-block;
  margin: 0 0 0.35rem;
}

.page-boundaries .timeline-impact {
  margin: 0;
  font-size: 0.95rem;
}

.page-boundaries .step-list {
  list-style: none;
  margin: 0 0 1rem;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1.1rem;
}

.page-boundaries .step-list .step-item {
  margin: 0;
  padding: 1rem 1.1rem;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  min-width: 0;
}

.page-boundaries .step-list .step-index {
  display: inline-block;
  font-family: var(--font-mono);
  font-size: 0.85rem;
  font-weight: 700;
  color: var(--status);
  background-color: var(--bg-mono);
  padding: 0.15rem 0.5rem;
  border-radius: var(--radius-sm);
  margin-bottom: 0.5rem;
}

.page-boundaries .step-list .step-title {
  font-size: 1rem;
  margin: 0 0 0.4rem;
}

.page-boundaries .step-list .step-desc {
  margin: 0;
  font-size: 0.92rem;
  color: var(--text-sub);
}

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

.error-main {
  display: flex;
  justify-content: center;
  padding-top: 3rem;
  padding-bottom: 4rem;
}

.error-block {
  max-width: 600px;
  width: 100%;
  background-color: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 2.25rem 1.75rem;
  text-align: left;
}

.error-code {
  font-family: var(--font-mono);
  font-size: 2.4rem;
  font-weight: 700;
  color: var(--accent);
  margin: 0 0 0.5rem;
  line-height: 1;
}

.error-block h1 {
  font-size: 1.5rem;
  margin: 0 0 0.6rem;
}

.error-text {
  color: var(--text-sub);
  margin: 0 0 1.25rem;
}

.error-actions {
  display: flex;
  flex-wrap: wrap;
  gap: 0.75rem;
  margin-bottom: 1.5rem;
}

.error-links {
  list-style: none;
  margin: 0;
  padding: 1.25rem 0 0;
  border-top: 1px solid var(--border);
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 0.6rem 1rem;
}

.error-links li {
  margin: 0;
  font-size: 0.92rem;
}

/* ============================================================
   responsive · 900px
   ============================================================ */

@media (max-width: 900px) {
  .header-inner {
    flex-wrap: wrap;
    gap: 0.75rem;
  }

  .nav-toggle {
    display: block;
    margin-left: auto;
  }

  .site-nav {
    order: 3;
    flex-basis: 100%;
  }

  .nav-list {
    display: none;
    flex-direction: column;
    align-items: stretch;
    gap: 0;
    padding: 0.5rem 0 0.75rem;
    border-top: 1px solid var(--border);
  }

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

  .nav-list a {
    display: block;
    padding: 0.7rem 0.25rem;
    min-height: 44px;
    border-bottom: 1px solid var(--border);
    border-left: 2px solid transparent;
    font-size: 1rem;
  }

  .nav-list a.is-current {
    border-bottom-color: var(--border);
    border-left-color: var(--accent);
    padding-left: 0.6rem;
  }

  .header-tools {
    margin-left: 0;
  }

  .hero-section {
    grid-template-columns: minmax(0, 1fr);
    gap: 1.5rem;
  }

  .page-layout,
  .page-layout.sidebar-left,
  .sidebar-left .page-layout {
    grid-template-columns: minmax(0, 1fr);
    gap: 1.5rem;
  }

  .page-sidebar,
  .page-aside {
    position: static;
    order: 2;
  }

  .page-body,
  .page-content {
    order: 1;
  }

  .page-playlists .page-aside {
    order: 1;
  }

  .page-playlists .page-aside .aside-toggle {
    display: block;
  }

  .page-playlists .page-aside .aside-body {
    display: none;
    margin-top: 0.75rem;
  }

  .page-playlists .page-aside .aside-body.is-open {
    display: block;
  }

  .playlist-grid,
  .page-playlists .playlist-cards,
  .path-overview .step-list,
  .page-guide .path-steps,
  .page-guide .back-list,
  .page-boundaries .step-list {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }

  .changelog-item {
    grid-template-columns: 7.5rem minmax(0, 1fr);
  }

  .changelog-desc {
    grid-column: 1 / -1;
  }

  .changelog-link {
    grid-column: 1 / -1;
  }
}

/* ============================================================
   responsive · 600px
   ============================================================ */

@media (max-width: 600px) {
  body {
    font-size: 0.97rem;
  }

  .site-main {
    padding: 1.25rem 1rem 2.5rem;
  }

  .header-inner {
    padding: 0.6rem 1rem;
  }

  .brand {
    font-size: 1rem;
  }

  .header-tools .tool-link.back-top {
    display: none;
  }

  h1,
  .hero-title,
  .page-title {
    font-size: 1.5rem;
  }

  h2 {
    font-size: 1.2rem;
  }

  .hero-section {
    padding-bottom: 1.5rem;
    margin-bottom: 1.75rem;
  }

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

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

  .direction-summary {
    padding: 1rem 1.1rem;
  }

  .section-block {
    margin-bottom: 2rem;
  }

  .playlist-grid,
  .page-playlists .playlist-cards,
  .path-overview .step-list,
  .page-guide .path-steps,
  .page-guide .back-list,
  .page-boundaries .step-list,
  .page-channels .tips-columns,
  .next-list,
  .error-links {
    grid-template-columns: minmax(0, 1fr);
  }

  .changelog-item {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.35rem;
  }

  .changelog-type {
    justify-self: start;
  }

  .page-channels .pair-row {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.2rem;
  }

  .page-guide .step-rows {
    grid-template-columns: minmax(0, 1fr);
    gap: 0.15rem;
  }

  .page-guide .step-rows dd {
    margin-bottom: 0.6rem;
  }

  .footer-inner {
    grid-template-columns: minmax(0, 1fr);
    gap: 1.5rem;
    padding: 1.75rem 1rem 1rem;
  }

  .footer-desc {
    max-width: none;
  }

  .footer-bottom {
    flex-direction: column;
    align-items: flex-start;
  }

  .error-block {
    padding: 1.75rem 1.25rem;
  }

  .error-code {
    font-size: 2rem;
  }

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

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

  .data-table th,
  .data-table td,
  .page-playlists .mapping-table th,
  .page-playlists .mapping-table td {
    padding: 0.6rem 0.7rem;
  }
}

/* ============================================================
   enhancement · motion (non-blocking)
   ============================================================ */

@media (prefers-reduced-motion: no-preference) {
  .section-block,
  .content-section,
  .page-playlists .section {
    animation: soft-rise 0.4s ease-out both;
  }
}

@keyframes soft-rise {
  from {
    transform: translateY(6px);
  }
  to {
    transform: translateY(0);
  }
}