:root {
  --paper: #fbfaf6;
  --paper-deep: #f4f1e9;
  --ink: #12345a;
  --ink-strong: #08284d;
  --muted: #5e6e70;
  --teal: #2b6867;
  --teal-soft: #e7efed;
  --amber: #a95013;
  --amber-soft: #f6e9dc;
  --blue-soft: #e8eef5;
  --green-soft: #e7f0e9;
  --line: #cfd7d3;
  --line-strong: #a9b8b4;
  --warning: #9f4f37;
  --warning-soft: #f7e9e3;
  --sidebar-width: 286px;
  --content-max: 1120px;
  --radius: 8px;
  color-scheme: light;
  font-family:
    -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC",
    "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  font-synthesis: none;
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  background: var(--paper);
}

body {
  margin: 0;
  color: var(--ink);
  background:
    linear-gradient(rgba(251, 250, 246, 0.95), rgba(251, 250, 246, 0.95)),
    var(--paper);
  font-size: 16px;
  line-height: 1.75;
  text-rendering: optimizeLegibility;
}

a {
  color: inherit;
  text-underline-offset: 0.18em;
}

button,
input {
  font: inherit;
}

button,
a,
input,
summary {
  -webkit-tap-highlight-color: transparent;
}

:focus-visible {
  outline: 3px solid #c8782f;
  outline-offset: 3px;
}

.skip-link {
  position: fixed;
  z-index: 100;
  top: 12px;
  left: 12px;
  padding: 10px 14px;
  color: #fff;
  background: var(--ink-strong);
  transform: translateY(-160%);
}

.skip-link:focus {
  transform: translateY(0);
}

.mobile-header {
  display: none;
}

.site-shell {
  min-height: 100vh;
}

.sidebar {
  position: fixed;
  z-index: 20;
  inset: 0 auto 0 0;
  width: var(--sidebar-width);
  padding: 42px 30px 28px;
  overflow-y: auto;
  border-right: 1px solid var(--line);
  background: rgba(251, 250, 246, 0.97);
}

.brand-block {
  padding-bottom: 24px;
}

.brand {
  display: inline-flex;
  flex-direction: column;
  gap: 0;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: clamp(2rem, 3.2vw, 2.7rem);
  font-weight: 700;
  line-height: 1.08;
  letter-spacing: 0.04em;
  text-decoration: none;
}

.brand-rule {
  display: none;
}

.brand-block p,
.nav-label {
  margin: 0;
  color: var(--teal);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  letter-spacing: 0.05em;
}

.age-nav {
  margin-top: 24px;
  padding-bottom: 6px;
}

#sidebar-age-links {
  display: grid;
  gap: 5px;
  margin-top: 14px;
}

#sidebar-age-links a {
  position: relative;
  min-height: 50px;
  padding: 10px 12px 10px 16px;
  border-radius: 5px;
  color: var(--teal);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.08rem;
  text-decoration: none;
  transition: background 160ms ease, color 160ms ease;
}

#sidebar-age-links a:hover {
  background: var(--paper-deep);
}

#sidebar-age-links a[aria-current="location"] {
  color: var(--ink-strong);
  background: var(--blue-soft);
}

#sidebar-age-links a[aria-current="location"]::before {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  left: -30px;
  width: 5px;
  background: var(--ink);
}

.secondary-nav {
  display: grid;
  gap: 4px;
  margin-top: 12px;
  padding-top: 12px;
  padding-bottom: 8px;
}

.secondary-nav a {
  min-height: 44px;
  padding: 8px 5px;
  text-decoration: none;
}

.secondary-nav a:hover {
  text-decoration: underline;
}

.sidebar-meta {
  display: grid;
  justify-items: start;
  gap: 7px;
  margin-top: 22px;
  font-size: 0.78rem;
}

.sidebar-meta p {
  margin: 0;
  color: var(--muted);
}

main {
  min-width: 0;
  margin-left: var(--sidebar-width);
  padding: 52px clamp(34px, 6vw, 92px) 34px;
}

main > * {
  width: min(100%, var(--content-max));
  margin-right: auto;
  margin-left: auto;
}

.intro {
  display: block;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--teal);
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0.16em;
  text-transform: uppercase;
}

h1,
h2,
h3 {
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  text-wrap: balance;
}

h1 {
  max-width: 780px;
  margin: 0;
  font-size: clamp(2.35rem, 3.2vw, 2.85rem);
  font-weight: 700;
  line-height: 1.1;
  letter-spacing: 0.015em;
}

h2 {
  margin: 0;
  font-size: clamp(2rem, 3.8vw, 3.15rem);
  font-weight: 600;
  line-height: 1.2;
}

h3 {
  margin: 0;
  font-size: 1.14rem;
  line-height: 1.45;
}

.lede {
  max-width: 700px;
  margin: 20px 0 0;
  color: var(--ink);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.1rem;
  line-height: 1.9;
}

.inline-status {
  max-width: 840px;
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.65;
}

.inline-status strong {
  color: var(--amber);
}

.inline-status a {
  color: var(--teal);
  font-weight: 600;
}

.timeline {
  margin-top: 50px;
  padding: 0 18px;
}

#timeline-links {
  position: relative;
  display: grid;
  grid-template-columns: repeat(6, 1fr);
}

#timeline-links::before {
  content: "";
  position: absolute;
  top: 7px;
  right: 8%;
  left: 8%;
  height: 1px;
  background: var(--teal);
}

#timeline-links a {
  position: relative;
  z-index: 1;
  display: grid;
  justify-items: center;
  gap: 12px;
  min-height: 54px;
  color: var(--teal);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  text-decoration: none;
}

#timeline-links a::before {
  content: "";
  width: 14px;
  height: 14px;
  border: 2px solid var(--teal);
  border-radius: 50%;
  background: var(--paper);
}

#timeline-links a[aria-current="location"] {
  color: var(--ink-strong);
  font-weight: 700;
}

#timeline-links a[aria-current="location"]::before {
  border-color: var(--ink-strong);
  background: var(--ink-strong);
}

.age-guides {
  margin-top: 38px;
}

.age-stage {
  scroll-margin-top: 28px;
  padding: 26px 0 52px;
}

.age-stage[hidden] {
  display: none;
}

.age-stage--detailed {
  padding-bottom: 30px;
}

.age03-title-block {
  max-width: 810px;
  margin: 20px 0 24px;
}

.age03-title-block h3 {
  font-size: clamp(1.7rem, 3vw, 2.45rem);
}

.age03-title-block p {
  margin: 10px 0 0;
  color: var(--muted);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.03rem;
}

.age03-title-block .age03-lead {
  margin-top: 18px;
  color: var(--ink-strong);
  font-size: 1.13rem;
}

.guide-subnav {
  position: sticky;
  z-index: 10;
  top: 0;
  display: flex;
  gap: 4px;
  margin: 0;
  padding: 8px 0;
  overflow-x: auto;
  background: rgba(251, 250, 246, 0.96);
  backdrop-filter: blur(8px);
}

.guide-subnav a {
  flex: 0 0 auto;
  min-height: 42px;
  padding: 7px 12px;
  border-radius: 3px;
  color: var(--teal);
  font-size: 0.86rem;
  font-weight: 700;
  text-decoration: none;
}

.guide-subnav a:hover {
  background: var(--teal-soft);
}

.age03-section {
  scroll-margin-top: 76px;
  padding: 32px 0;
}

.guide-subnav + .age03-section {
  padding-top: 18px;
}

.age03-section > .eyebrow {
  margin-bottom: 8px;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: clamp(1.75rem, 3vw, 2.35rem);
  font-weight: 600;
  letter-spacing: 0.02em;
  text-transform: none;
}

.age03-section > h3 {
  max-width: 800px;
  color: var(--muted);
  font-family: inherit;
  font-size: clamp(1.05rem, 1.7vw, 1.3rem);
  font-weight: 500;
}

.section-intro-text {
  max-width: 760px;
  margin: 10px 0 22px;
  color: var(--muted);
}

.secondary-section-title {
  margin-top: 34px;
}

.development-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 22px;
}

.development-card {
  min-height: 160px;
  padding: 19px 20px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.development-card h4,
.theme-body h4,
.material-row h4,
.daily-window h4,
.signal-card h4,
.age03-safety-card h4,
.age03-source h4 {
  margin: 0;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.1rem;
}

.development-card p {
  margin: 10px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.draft-evidence-note,
.judgment-note {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr);
  gap: 16px;
  align-items: start;
  margin-top: 24px;
  padding: 18px 20px;
  background: var(--paper-deep);
}

.draft-evidence-note p,
.judgment-note p {
  margin: 0;
  color: var(--muted);
}

.interaction-themes {
  display: grid;
  gap: 8px;
  margin-top: 22px;
}

.interaction-theme {
  margin: 0;
  padding: 0;
  border-radius: var(--radius);
  background: rgba(244, 241, 233, 0.62);
}

.interaction-theme > summary {
  display: grid;
  grid-template-columns: 54px minmax(0, 1fr);
  gap: 18px;
  align-items: center;
  min-height: 72px;
  padding: 10px 16px;
  list-style: none;
}

.interaction-theme > summary::-webkit-details-marker {
  display: none;
}

.interaction-theme > summary::after {
  content: "展开";
  grid-column: 3;
  color: var(--teal);
  font-size: 0.78rem;
}

.interaction-theme[open] > summary::after {
  content: "收起";
}

.interaction-theme > summary strong {
  display: block;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.2rem;
}

.interaction-theme > summary small {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-weight: 400;
}

.theme-number {
  color: var(--amber);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.4rem;
}

.theme-body {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 20px 32px;
  padding: 4px 18px 22px 70px;
}

.theme-body p,
.theme-body ul {
  margin-top: 8px;
}

.theme-body li + li {
  margin-top: 4px;
}

.theme-body blockquote {
  margin: 14px 0 0;
  padding: 12px 16px;
  color: var(--teal);
  border-left: 2px solid var(--teal);
  background: var(--teal-soft);
}

.theme-toy-gallery {
  margin-top: 16px;
}

.theme-toy-gallery__label {
  margin: 0 0 9px !important;
  color: var(--muted);
  font-size: 0.78rem;
}

.theme-toy-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.theme-toy-card {
  display: grid;
  min-width: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  color: var(--teal);
  text-decoration: none;
  background: rgba(255, 255, 255, 0.55);
}

.theme-toy-card img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1;
  object-fit: contain;
  background: #fff;
}

.theme-toy-card span {
  padding: 8px 9px 9px;
  font-size: 0.78rem;
  line-height: 1.45;
}

.theme-toy-card:hover,
.theme-toy-card:focus-visible {
  border-color: var(--teal);
  background: var(--teal-soft);
}

.inline-toy-link {
  color: var(--teal);
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.inline-toy-link:hover,
.inline-toy-link:focus-visible {
  color: var(--ink-strong);
}

.interaction-rhythm {
  display: grid;
  gap: 3px;
  padding: 12px 14px;
  color: #6f3d20;
  background: var(--amber-soft);
}

.avoid-block {
  grid-column: 1 / -1;
  padding: 15px 16px;
  background: var(--warning-soft);
}

.materials-list {
  display: grid;
  gap: 8px;
}

.material-row {
  display: grid;
  grid-template-columns: 56px minmax(0, 1fr);
  gap: 18px;
  padding: 18px 20px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.material-index {
  color: var(--teal);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.2rem;
}

.material-title-line {
  display: flex;
  justify-content: space-between;
  gap: 18px;
  align-items: start;
}

.material-level {
  flex: 0 0 auto;
  padding: 3px 9px;
  border-radius: 999px;
  font-size: 0.72rem;
  font-weight: 700;
}

.material-level--essential {
  color: #fff;
  background: var(--teal);
}

.material-level--recommended {
  color: #754511;
  background: var(--amber-soft);
}

.material-level--optional {
  color: var(--muted);
  background: #ecefed;
}

.material-row p {
  margin: 8px 0 0;
  color: var(--muted);
}

.material-gallery {
  margin-top: 42px;
  padding-top: 32px;
}

.material-gallery > h3 {
  max-width: 800px;
  font-size: clamp(1.7rem, 3vw, 2.4rem);
}

.material-gallery__disclaimer {
  max-width: 860px;
  margin: 18px 0 0;
  padding: 20px 22px;
  color: #68382d;
  border-left: 4px solid var(--warning);
  background: var(--warning-soft);
}

.material-gallery__source-note {
  max-width: 820px;
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.88rem;
}

.material-example-categories {
  margin-top: 28px;
}

.material-example-category {
  padding: 28px 0 32px;
}

.material-example-category__heading {
  display: flex;
  gap: 14px;
  align-items: baseline;
  margin-bottom: 20px;
}

.material-example-category__heading span {
  color: var(--amber);
  font-family: "Songti SC", "STSong", "SimSun", serif;
}

.material-example-category__heading h4 {
  margin: 0;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.35rem;
}

.material-example-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 16px;
}

.material-example-card {
  min-width: 0;
  margin: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: #fff;
}

.material-example-card img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1 / 1;
  object-fit: cover;
  background: var(--paper-deep);
}

.material-example-card figcaption {
  padding: 16px;
}

.material-example-card__meta {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  color: var(--muted);
  font-size: 0.74rem;
}

.material-example-priority {
  display: inline-flex;
  align-items: center;
  min-height: 25px;
  padding: 2px 9px;
  border-radius: 999px;
  font-weight: 700;
}

.material-example-priority--recommended {
  color: #754511;
  background: var(--amber-soft);
}

.material-example-priority--optional {
  color: var(--teal);
  background: var(--teal-soft);
}

.material-example-card h5 {
  margin: 12px 0 0;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.16rem;
}

.material-example-card figcaption > p {
  margin: 8px 0 0;
  color: var(--muted);
  font-size: 0.9rem;
}

.material-example-notes {
  margin: 14px 0 0;
  padding: 0;
  border-bottom: 0;
}

.material-example-notes summary {
  width: fit-content;
  min-height: 36px;
  font-size: 0.82rem;
}

.material-example-notes p {
  margin: 6px 0 0;
  padding: 12px 14px;
  color: var(--muted);
  background: var(--paper-deep);
  font-size: 0.82rem;
}

.material-gallery__mobile-warning {
  max-width: 860px;
  margin: 20px 0 0;
  padding: 16px 18px;
  color: #68382d;
  background: var(--warning-soft);
  font-size: 0.88rem;
}

.toy-showcase-list {
  display: grid;
  gap: 12px;
  margin-top: 24px;
}

.toy-showcase-row {
  display: grid;
  grid-template-columns: minmax(220px, 0.8fr) minmax(0, 1.5fr);
  gap: 32px;
  padding: 26px 22px;
  scroll-margin-top: 112px;
  border-radius: var(--radius);
  background: rgba(244, 241, 233, 0.55);
}

.toy-showcase-copy {
  min-width: 0;
}

.toy-showcase-copy .material-title-line {
  margin-top: 10px;
}

.toy-showcase-copy > p {
  margin: 12px 0 0;
  color: var(--muted);
}

.toy-showcase-copy .toy-library-link {
  display: inline-flex;
  margin-top: 18px;
}

.toy-example-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 18px;
  align-items: start;
}

.daily-timeline {
  position: relative;
  display: grid;
  gap: 0;
  margin-top: 28px;
}

.daily-timeline::before {
  content: "";
  position: absolute;
  top: 30px;
  bottom: 30px;
  left: 24px;
  width: 1px;
  background: var(--line-strong);
}

.daily-window {
  position: relative;
  display: grid;
  grid-template-columns: 50px minmax(0, 1fr);
  gap: 24px;
  padding: 22px 0;
}

.daily-window__number {
  z-index: 1;
  display: grid;
  place-items: center;
  width: 48px;
  height: 48px;
  border: 1px solid var(--teal);
  border-radius: 50%;
  color: var(--teal);
  background: var(--paper);
  font-family: "Songti SC", "STSong", "SimSun", serif;
}

.daily-window__label {
  margin: 0;
  color: var(--amber);
  font-size: 0.8rem;
  font-weight: 700;
}

.daily-window h4 {
  margin-top: 2px;
  font-size: 1.25rem;
}

.daily-window p {
  margin: 8px 0 0;
  color: var(--muted);
}

.theme-tags {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  margin-top: 12px;
}

.theme-tags span {
  padding: 3px 9px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--teal);
  font-size: 0.76rem;
}

.flexible-plan-note {
  margin-top: 24px;
  padding: 20px 22px;
  color: #6f3d20;
  background: var(--amber-soft);
}

.signal-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
  margin-top: 22px;
}

.signal-card {
  padding: 20px 22px;
  border-radius: var(--radius);
}

.signal-card--continue {
  background: var(--green-soft);
}

.signal-card--pause {
  background: var(--warning-soft);
}

.signal-card ul {
  margin-bottom: 0;
}

.age03-safety-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin-top: 28px;
}

.age03-safety-card {
  padding: 24px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.age03-safety-card ul {
  margin-bottom: 0;
  padding-left: 1.2em;
}

.safety-source-warning {
  margin: 18px 0 0;
  color: var(--warning);
  font-size: 0.86rem;
}

.age03-source-list {
  display: grid;
  gap: 8px;
  margin-top: 24px;
}

.age03-source {
  display: grid;
  grid-template-columns: minmax(190px, 0.8fr) minmax(0, 1.6fr);
  gap: 10px 34px;
  padding: 18px 20px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.age03-source p {
  margin: 0;
  color: var(--muted);
}

.age03-source .source-keywords {
  grid-column: 2;
  font-size: 0.82rem;
}

.age-stage:first-child {
  padding-top: 0;
  border-top: 0;
}

.stage-header {
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  gap: 28px;
  align-items: end;
}

.stage-number {
  margin: 0;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: clamp(3.6rem, 8vw, 6.3rem);
  line-height: 0.95;
  letter-spacing: -0.04em;
}

.stage-number small {
  font-size: 0.35em;
  letter-spacing: 0.04em;
}

.stage-actions {
  display: flex;
  gap: 8px;
}

.copy-link,
.text-button {
  min-height: 44px;
  padding: 8px 13px;
  border: 1px solid var(--line-strong);
  border-radius: 4px;
  color: var(--teal);
  background: transparent;
  cursor: pointer;
}

.copy-link:hover,
.text-button:hover {
  background: var(--teal-soft);
}

.ability-line {
  margin: 22px 0 28px;
  color: var(--amber);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: clamp(1rem, 2vw, 1.25rem);
  letter-spacing: 0.08em;
}

.sample-disclaimer {
  display: flex;
  gap: 12px;
  align-items: flex-start;
  margin: 0 0 22px;
  padding: 12px 16px;
  color: #6f3d20;
  background: var(--amber-soft);
  border-radius: var(--radius);
  font-size: 0.88rem;
}

.sample-disclaimer strong {
  flex: 0 0 auto;
}

.core-list {
  display: grid;
  gap: 7px;
}

.core-row {
  display: grid;
  grid-template-columns: 44px minmax(170px, 0.7fr) minmax(260px, 1.3fr);
  gap: 14px;
  align-items: start;
  min-height: 64px;
  padding: 13px 16px;
  border-radius: 6px;
  background: var(--paper-deep);
}

.core-row__index {
  color: var(--teal);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.25rem;
}

.core-row a {
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
  font-size: 1.08rem;
  text-decoration: none;
}

.core-row a:hover {
  text-decoration: underline;
}

.core-row__title {
  display: flex;
  flex-wrap: wrap;
  gap: 7px 9px;
  align-items: center;
}

.core-row__action {
  color: var(--muted);
  font-size: 0.82rem;
  line-height: 1.65;
}

.section-library-link {
  display: inline-flex;
  margin-top: 15px;
  color: var(--teal);
  font-size: 0.85rem;
  font-weight: 700;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.continue-note,
.stage-guidance {
  margin-top: 24px;
  padding-left: 18px;
  border-left: 2px solid var(--line-strong);
}

.continue-note h3,
.stage-guidance h3 {
  margin-bottom: 6px;
}

.continue-note p,
.stage-guidance p {
  margin: 0;
  color: var(--muted);
}

.stage-guidance ul {
  margin: 8px 0 0;
  padding-left: 1.2rem;
  color: var(--muted);
}

.continue-note a {
  color: var(--teal);
}

.stage-footer-nav {
  display: flex;
  justify-content: space-between;
  gap: 16px;
  margin-top: 26px;
  padding-top: 12px;
}

.stage-footer-nav a {
  min-height: 44px;
  color: var(--teal);
  font-weight: 600;
}

.section-divider {
  scroll-margin-top: 28px;
  padding: 54px 0;
}

.section-heading {
  display: flex;
  justify-content: space-between;
  gap: 28px;
  align-items: flex-end;
  margin-bottom: 26px;
}

.section-heading p:not(.eyebrow) {
  max-width: 660px;
  margin: 10px 0 0;
  color: var(--muted);
}

.filter-panel {
  display: grid;
  grid-template-columns: 140px minmax(260px, 1fr);
  gap: 14px 24px;
  align-items: center;
  padding: 18px 20px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.filter-panel > label,
.filter-panel legend {
  color: var(--ink-strong);
  font-weight: 700;
}

.filter-panel input {
  width: 100%;
  min-height: 50px;
  padding: 10px 14px;
  border: 1px solid var(--line-strong);
  border-radius: 4px;
  color: var(--ink-strong);
  background: #fff;
}

.filter-panel fieldset {
  display: contents;
}

.filter-panel legend {
  padding: 0;
}

.filter-buttons {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
}

.filter-button {
  min-height: 44px;
  padding: 8px 14px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--teal);
  background: transparent;
  cursor: pointer;
}

.filter-button[aria-pressed="true"] {
  color: #fff;
  border-color: var(--teal);
  background: var(--teal);
}

.result-count {
  min-height: 28px;
  margin: 20px 0 6px;
  color: var(--muted);
  font-size: 0.86rem;
}

.category-age-guidance {
  margin: 10px 0 20px;
  padding: 20px;
  border-radius: var(--radius);
  background: var(--teal-soft);
}

.category-age-guidance[hidden] {
  display: none;
}

.category-age-guidance h3 {
  margin-top: 4px;
  font-size: 1.35rem;
}

.age-guidance-groups {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin-top: 14px;
}

.age-guidance-groups > div {
  padding: 12px 14px;
  border-radius: 5px;
  background: rgba(255, 255, 255, 0.62);
}

.age-guidance-groups strong {
  color: var(--ink-strong);
}

.age-guidance-groups p,
.age-guidance-conclusion {
  margin: 4px 0 0;
  color: var(--muted);
  font-size: 0.82rem;
}

.age-guidance-reuse {
  margin: 12px 0 0;
  color: var(--muted);
  font-size: 0.82rem;
}

.age-guidance-conclusion {
  padding-top: 12px;
}

.category-index {
  display: grid;
  gap: 12px;
}

.category-detail {
  scroll-margin-top: 28px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) minmax(190px, 260px);
  gap: clamp(24px, 4vw, 58px);
  padding: 26px 24px;
  border-radius: var(--radius);
  background: rgba(244, 241, 233, 0.52);
}

.category-detail--text-only {
  grid-template-columns: minmax(0, 1fr);
}

.category-detail[hidden] {
  display: none;
}

.category-kicker {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  align-items: center;
  margin: 0 0 5px;
  color: var(--teal);
  font-size: 0.76rem;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.category-active-priority {
  padding: 2px 8px;
  border-radius: 999px;
  letter-spacing: 0;
  font-size: 0.68rem;
}

.category-active-priority[data-priority-level="0"] {
  color: #754511;
  background: var(--amber-soft);
}

.category-active-priority[data-priority-level="1"] {
  color: var(--muted);
  background: #e8eceb;
}

.category-detail h3 {
  font-size: clamp(1.4rem, 2.5vw, 1.85rem);
}

.category-en {
  margin: 4px 0 16px;
  color: var(--muted);
  font-size: 0.82rem;
}

.category-definition {
  max-width: 680px;
  margin: 0;
  color: var(--ink);
}

.category-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 22px;
  margin-top: 20px;
  color: var(--muted);
  font-size: 0.85rem;
}

.category-links {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  margin-top: 14px;
}

.category-links a {
  min-height: 38px;
  padding: 5px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--teal);
  text-decoration: none;
}

.category-links a:hover {
  background: var(--teal-soft);
}

.category-stage-guidance {
  margin-top: 18px;
  padding-top: 12px;
  border-top: 1px solid var(--line);
}

.category-stage-guidance > summary {
  color: var(--teal);
  cursor: pointer;
  font-size: 0.82rem;
  font-weight: 700;
}

.category-stage-guidance > div {
  display: grid;
  gap: 8px;
  margin-top: 10px;
}

.category-stage-guidance__item {
  padding: 10px 12px;
  border-radius: 5px;
  background: rgba(255, 255, 255, 0.58);
}

.category-stage-guidance__item > div {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
  align-items: center;
}

.category-stage-guidance__item a {
  color: var(--teal);
  font-weight: 700;
}

.category-stage-guidance__item span {
  padding: 2px 7px;
  border-radius: 999px;
  color: var(--muted);
  background: var(--paper-deep);
  font-size: 0.68rem;
}

.category-stage-guidance__item p {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.55;
}

.category-image {
  align-self: center;
  margin: 0;
}

.category-example-stack {
  display: grid;
  gap: 14px;
  align-self: start;
}

.category-image img {
  display: block;
  width: 100%;
  height: auto;
  aspect-ratio: 1;
  object-fit: contain;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.section-source-panel {
  margin-top: 22px;
  padding: 0 18px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.section-source-panel > summary {
  padding: 13px 0;
  color: var(--teal);
  cursor: pointer;
  font-weight: 700;
}

.section-source-panel__body {
  padding: 0 0 18px;
}

.section-source-panel__body > p {
  max-width: 820px;
  margin: 0 0 16px;
  color: var(--muted);
  font-size: 0.84rem;
}

.stage-source-list {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin: 0;
  list-style: none;
}

.stage-source-list li {
  padding: 13px 14px;
  border-radius: 6px;
  background: var(--paper);
}

.stage-source-list strong {
  display: block;
  color: var(--ink-strong);
  font-family: "Songti SC", "STSong", "SimSun", serif;
}

.stage-source-list span {
  display: block;
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.8rem;
}

.source-cite {
  display: inline-flex;
  margin-top: 12px;
  color: var(--teal);
  font-size: 0.76rem;
  font-weight: 700;
  text-decoration-thickness: 1px;
  text-underline-offset: 3px;
}

.category-image figcaption {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.72rem;
  line-height: 1.5;
}

.category-example-caption strong,
.category-example-caption > span {
  display: block;
}

.category-example-caption strong {
  color: var(--ink-strong);
  font-size: 0.82rem;
}

.category-example-caption > span {
  margin-top: 3px;
}

.category-example-notes {
  margin-top: 7px;
}

.category-example-notes summary {
  width: fit-content;
  color: var(--teal);
  cursor: pointer;
  font-weight: 700;
}

.category-example-notes p {
  margin: 6px 0 0;
  color: var(--muted);
}

.category-placeholder {
  display: grid;
  place-items: center;
  min-height: 150px;
  padding: 20px;
  border: 1px dashed var(--line-strong);
  border-radius: var(--radius);
  color: var(--muted);
  text-align: center;
  font-size: 0.82rem;
}

.source-key {
  display: inline-flex;
  align-items: center;
  min-height: 26px;
  padding: 3px 9px;
  border: 1px solid currentColor;
  border-radius: 3px;
  font-size: 0.72rem;
  font-weight: 700;
  line-height: 1.2;
}

.source-key--brief {
  color: #795f2f;
  background: #f3eddd;
}

.source-key--fact {
  color: #315f8b;
  background: var(--blue-soft);
}

.source-key--recommendation {
  color: #7b542a;
  background: var(--amber-soft);
}

.source-key--pending {
  color: #5f6767;
  background: #eff1f0;
  border-style: dashed;
}

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

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

.source-state--single > div {
  max-width: 760px;
}

.source-state > div {
  padding: 22px;
  border-radius: var(--radius);
  background: var(--paper-deep);
}

.source-state > div + div {
  padding-left: 22px;
}

.source-state h3 {
  margin-top: 14px;
}

.source-state p {
  margin: 8px 0 0;
  color: var(--muted);
}

.reference-book-list {
  display: grid;
  gap: 8px;
  margin: 18px 0;
  padding-left: 1.4rem;
  color: var(--ink-strong);
}

.reference-book-list li::marker {
  color: var(--amber);
  font-variant-numeric: tabular-nums;
}

details {
  margin-top: 16px;
  padding: 0 0 14px;
}

summary {
  min-height: 44px;
  color: var(--teal);
  font-weight: 700;
  cursor: pointer;
}

details > :not(summary) {
  max-width: 760px;
}

code {
  padding: 0.1em 0.35em;
  border-radius: 3px;
  color: var(--ink-strong);
  background: var(--paper-deep);
}

.safety-callout {
  max-width: 820px;
  padding: 24px 26px;
  border-left: 4px solid var(--warning);
  background: var(--warning-soft);
}

.safety-callout p {
  margin: 8px 0 0;
  color: #68382d;
}

.global-safety-grid {
  grid-template-columns: repeat(2, minmax(0, 1fr));
  max-width: 980px;
}

.changelog-item {
  display: grid;
  grid-template-columns: 130px minmax(0, 1fr);
  gap: 24px;
  padding: 20px 0;
}

.changelog-item:last-child {
  padding-bottom: 0;
}

.changelog-item p {
  margin: 0;
}

.changelog-item time {
  display: block;
  color: var(--muted);
  font-size: 0.82rem;
}

footer {
  display: flex;
  justify-content: space-between;
  gap: 22px;
  align-items: center;
  padding-top: 34px;
  color: var(--muted);
  font-size: 0.84rem;
}

footer a {
  color: var(--teal);
  font-weight: 700;
}

.toast {
  position: fixed;
  z-index: 50;
  right: 22px;
  bottom: 22px;
  max-width: 320px;
  padding: 11px 15px;
  border-radius: 4px;
  color: #fff;
  background: var(--ink-strong);
  opacity: 0;
  transform: translateY(12px);
  pointer-events: none;
  transition: opacity 150ms ease, transform 150ms ease;
}

.toast.is-visible {
  opacity: 1;
  transform: translateY(0);
}

.no-script-note {
  padding: 24px;
  border: 1px solid var(--line);
  background: var(--paper-deep);
}

@media (max-width: 980px) {
  :root {
    --sidebar-width: 240px;
  }

  .sidebar {
    padding-right: 22px;
    padding-left: 22px;
  }

  #sidebar-age-links a[aria-current="location"]::before {
    left: -22px;
  }

  main {
    padding-right: 34px;
    padding-left: 34px;
  }

}

@media (max-width: 760px) {
  body {
    padding-top: 58px;
  }

  .mobile-header {
    position: fixed;
    z-index: 40;
    inset: 0 0 auto;
    display: flex;
    justify-content: space-between;
    align-items: center;
    height: 58px;
    padding: 0 16px;
    border-bottom: 1px solid var(--line);
    background: rgba(251, 250, 246, 0.98);
  }

  .mobile-brand {
    color: var(--ink-strong);
    font-family: "Songti SC", "STSong", "SimSun", serif;
    font-weight: 700;
    text-decoration: none;
  }

  .menu-button {
    min-width: 52px;
    min-height: 44px;
    border: 1px solid var(--line-strong);
    border-radius: 4px;
    color: var(--teal);
    background: transparent;
  }

  .sidebar {
    top: 58px;
    width: min(88vw, 320px);
    padding-top: 28px;
    transform: translateX(-110%);
    transition: transform 180ms ease;
    box-shadow: 8px 0 24px rgba(8, 40, 77, 0.08);
  }

  .sidebar.is-open {
    transform: translateX(0);
  }

  .brand-block {
    display: none;
  }

  main {
    margin-left: 0;
    padding: 38px 20px 30px;
  }

  .timeline {
    margin-top: 36px;
    padding: 0;
    overflow-x: auto;
  }

  #timeline-links {
    width: 630px;
  }

  .age-guides {
    margin-top: 38px;
  }

  .stage-header {
    grid-template-columns: 1fr;
    align-items: start;
  }

  .guide-subnav {
    top: 58px;
    margin-right: -20px;
    margin-left: -20px;
    padding-right: 16px;
    padding-left: 16px;
  }

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

  .development-card {
    min-height: 0;
  }

  .theme-body {
    grid-template-columns: 1fr;
    padding-left: 0;
  }

  .interaction-theme > summary {
    grid-template-columns: 44px minmax(0, 1fr);
  }

  .interaction-theme > summary::after {
    display: none;
  }

  .signal-grid,
  .age03-safety-grid {
    grid-template-columns: 1fr;
  }

  .material-example-grid {
    grid-template-columns: 1fr;
  }

  .toy-showcase-row {
    grid-template-columns: 1fr;
    gap: 24px;
  }

  .material-gallery {
    margin-top: 48px;
    padding-top: 44px;
  }

  .age03-source {
    grid-template-columns: 1fr;
  }

  .age03-source .source-keywords {
    grid-column: 1;
  }

  .stage-number {
    font-size: 3.9rem;
  }

  .core-row {
    grid-template-columns: 32px minmax(0, 1fr);
    padding: 10px 0;
  }

  .core-row__action {
    grid-column: 2;
    margin-top: -12px;
  }

  .section-heading {
    align-items: flex-start;
    flex-direction: column;
  }

  .filter-panel {
    grid-template-columns: 1fr;
  }

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

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

  .category-image {
    width: min(100%, 300px);
  }

  .source-state {
    grid-template-columns: 1fr;
  }

  .source-state > div {
    padding-right: 0;
  }

  .source-state > div + div {
    padding-left: 0;
    border-left: 0;
  }

  .changelog-item {
    grid-template-columns: 1fr;
    gap: 8px;
  }

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

@media (max-width: 640px) {
  .stage-source-list {
    grid-template-columns: 1fr;
  }
}

@media (max-width: 420px) {
  main {
    padding-right: 16px;
    padding-left: 16px;
  }

  .guide-subnav {
    margin-right: -16px;
    margin-left: -16px;
  }

  h1 {
    font-size: 2.45rem;
  }

  .stage-number {
    font-size: 3.35rem;
  }

  .sample-disclaimer {
    flex-direction: column;
  }

  .toy-example-grid {
    grid-template-columns: 1fr;
  }
}

@media (prefers-reduced-motion: reduce) {
  html {
    scroll-behavior: auto;
  }

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}

@media print {
  :root {
    --paper: #fff;
  }

  body {
    color: #000;
    background: #fff;
  }

  .mobile-header,
  .sidebar,
  .copy-link,
  .stage-actions,
  .filter-panel,
  .toast {
    display: none !important;
  }

  main {
    margin: 0;
    padding: 0;
  }

  details > * {
    display: block !important;
  }

  .age-stage,
  .category-detail,
  .info-section {
    break-inside: avoid;
  }

  a[href]::after {
    content: " (" attr(href) ")";
    color: #555;
    font-size: 0.8em;
  }
}