.learn-page {
  background: #f7f4ed;
}

.learn-main {
  width: var(--guide-content);
  margin-inline: auto;
  padding: 54px 0 90px;
}

.learn-introduction {
  display: grid;
  align-items: end;
  gap: 40px;
  grid-template-columns: minmax(0, 1fr) 250px;
  padding-bottom: 42px;
  border-bottom: 1px solid var(--line);
}

.learn-introduction > div {
  max-width: 820px;
}

.learn-introduction h1 {
  max-width: 780px;
  margin-bottom: 20px;
  font-size: clamp(2.7rem, 5vw, 4.8rem);
  line-height: 1;
}

.learn-lede {
  max-width: 760px;
  margin-bottom: 16px;
  color: #3f4c46;
  font-size: 1.15rem;
  line-height: 1.65;
}

.working-note {
  margin: 0;
  color: var(--muted);
  font-size: 0.84rem;
}

.learn-plan-picker,
.lesson-search {
  display: grid;
  gap: 7px;
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.learn-plan-picker select,
.lesson-search input {
  width: 100%;
  min-height: 46px;
  padding: 10px 12px;
  border: 1px solid var(--line-strong);
  border-radius: 8px;
  background: var(--paper-raised);
  color: var(--ink);
  font-size: 0.88rem;
  font-weight: 600;
  letter-spacing: 0;
  text-transform: none;
}

.guided-tour {
  display: grid;
  gap: 22px;
  padding: 30px;
  border-bottom: 1px solid var(--line);
  background: var(--blue-soft);
}

.guided-tour-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 28px;
}

.guided-tour-heading h2 {
  margin: 0;
  font-size: clamp(1.7rem, 3vw, 2.35rem);
}

.guided-tour-heading > p {
  max-width: 360px;
  margin: 0;
  color: var(--muted);
  font-size: 0.82rem;
}

.guided-tour ol {
  display: grid;
  gap: 8px;
  margin: 0;
  padding: 0;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  list-style: none;
}

.guided-tour button {
  display: grid;
  width: 100%;
  min-height: 52px;
  align-items: center;
  gap: 10px;
  padding: 10px 12px;
  border: 1px solid rgb(66 110 126 / 24%);
  border-radius: 7px;
  background: rgb(255 255 255 / 48%);
  grid-template-columns: 28px 1fr;
  text-align: left;
}

.guided-tour button:hover,
.guided-tour button[aria-current="step"] {
  border-color: var(--blue);
  background: var(--paper-raised);
}

.guided-tour button span {
  color: var(--coral);
  font-size: 0.64rem;
  font-weight: 850;
}

.guided-tour button strong {
  font-size: 0.78rem;
}

.lesson-layout {
  display: grid;
  align-items: start;
  gap: 28px;
  grid-template-columns: 220px minmax(360px, 1fr) minmax(390px, 0.92fr);
  padding-top: 34px;
}

.lesson-index,
.lesson-example {
  position: sticky;
  top: 20px;
}

.lesson-index {
  min-width: 0;
  max-height: calc(100vh - 40px);
  padding-right: 8px;
  overflow-y: auto;
}

.lesson-search {
  margin-bottom: 24px;
}

.lesson-search input {
  padding-inline: 10px;
  font-size: 0.78rem;
}

.topic-group + .topic-group {
  margin-top: 7px;
}

.topic-group summary {
  display: flex;
  min-height: 38px;
  align-items: center;
  justify-content: space-between;
  gap: 8px;
  padding: 7px 8px;
  border-radius: 6px;
  color: var(--muted);
  font-size: 0.68rem;
  font-weight: 850;
  letter-spacing: 0.09em;
  list-style: none;
  text-transform: uppercase;
}

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

.topic-group summary::after {
  color: var(--blue);
  content: "+";
  font-size: 0.9rem;
}

.topic-group[open] summary {
  color: var(--ink);
}

.topic-group[open] summary::after {
  content: "−";
}

.topic-group summary:hover {
  background: rgb(255 255 255 / 45%);
}

.topic-group summary small {
  margin-left: auto;
  color: var(--muted);
  font-size: 0.6rem;
  letter-spacing: 0;
}

.topic-group > div {
  padding-top: 3px;
}

.topic-group button {
  display: grid;
  width: 100%;
  min-height: 48px;
  gap: 1px;
  padding: 8px 10px;
  border: 0;
  border-left: 2px solid var(--line);
  background: transparent;
  text-align: left;
}

.topic-group button:hover {
  border-left-color: var(--line-strong);
  background: rgb(255 255 255 / 45%);
}

.topic-group button[aria-current="page"] {
  border-left-color: var(--coral);
  background: #fff;
}

.topic-group button span {
  font-size: 0.82rem;
  font-weight: 700;
}

.topic-group button code {
  color: var(--muted);
  font-size: 0.65rem;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.lesson-index-note,
.topic-empty {
  margin: 24px 10px 0;
  color: var(--muted);
  font-size: 0.74rem;
  line-height: 1.5;
}

.lesson-chapter {
  min-width: 0;
  padding: 4px 2px;
}

.chapter-header {
  padding-bottom: 30px;
  border-bottom: 1px solid var(--line);
}

.chapter-number,
.section-kicker {
  margin-bottom: 8px;
  color: var(--coral);
  font-size: 0.68rem;
  font-weight: 850;
  letter-spacing: 0.1em;
  text-transform: uppercase;
}

.chapter-path {
  margin-bottom: 14px;
}

.chapter-path code,
.example-path code {
  padding: 3px 6px;
  border-radius: 4px;
  background: var(--paper-deep);
  font-size: 0.76rem;
}

.chapter-header h2 {
  margin-bottom: 14px;
  font-size: clamp(2rem, 3.4vw, 3rem);
}

.chapter-summary {
  margin: 0;
  color: #3f4c46;
  font-size: 1.08rem;
  line-height: 1.6;
}

.chapter-prose,
.key-reference {
  padding-block: 30px;
  border-bottom: 1px solid var(--line);
}

.chapter-prose > h3,
.key-reference-heading h3 {
  font-family: inherit;
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: -0.01em;
}

.chapter-prose p {
  color: #33413b;
  line-height: 1.72;
}

.chapter-detail,
.chapter-sources {
  margin-top: 28px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.chapter-detail h4,
.chapter-sources h4 {
  margin: 0 0 8px;
  font-size: 0.9rem;
}

.chapter-detail p:first-of-type {
  margin-top: 0;
}

.chapter-sources ul {
  display: grid;
  gap: 12px;
  margin: 0;
  padding: 0;
  list-style: none;
}

.chapter-sources li {
  display: grid;
  gap: 2px;
}

.chapter-sources a {
  width: fit-content;
  color: var(--blue);
  font-size: 0.84rem;
  font-weight: 750;
  text-underline-offset: 3px;
}

.chapter-sources span {
  color: var(--muted);
  font-size: 0.78rem;
  line-height: 1.5;
}

.chapter-note {
  margin-top: 24px;
  padding: 16px 18px;
  border-left: 3px solid var(--gold);
  background: var(--gold-soft);
}

.chapter-note strong {
  display: block;
  margin-bottom: 4px;
  font-size: 0.76rem;
}

.chapter-note p {
  margin: 0;
  font-size: 0.84rem;
}

.related-topics {
  margin-top: 26px;
}

.related-topics h3 {
  margin-bottom: 8px;
  color: var(--muted);
  font-family: inherit;
  font-size: 0.72rem;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.related-topics > div {
  display: flex;
  flex-wrap: wrap;
  gap: 7px;
}

.related-topics button {
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgb(255 255 255 / 45%);
  color: var(--blue);
  font-size: 0.74rem;
  font-weight: 700;
}

.key-reference-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 20px;
  margin-bottom: 18px;
}

.key-reference-heading h3 {
  margin: 0;
}

.key-reference-heading a {
  color: var(--blue);
  font-size: 0.72rem;
  font-weight: 700;
  text-underline-offset: 3px;
}

.shape-description {
  margin-bottom: 18px;
  color: var(--muted);
  font-size: 0.84rem;
}

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

.key-row {
  padding: 15px 0;
  border-bottom: 1px solid var(--line);
}

.key-row header {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 7px;
}

.key-row header > code {
  color: var(--ink);
  font-size: 0.82rem;
  font-weight: 750;
}

.presence,
.type-label {
  padding: 2px 6px;
  border-radius: 4px;
  font-size: 0.61rem;
  font-weight: 800;
}

.presence.required {
  background: var(--coral-soft);
  color: #7c2f20;
}

.presence.optional {
  background: var(--paper-deep);
  color: var(--muted);
}

.type-label {
  color: var(--blue);
  background: var(--blue-soft);
}

.key-row p {
  margin: 7px 0 0;
  color: var(--muted);
  font-size: 0.8rem;
  line-height: 1.55;
}

.allowed-values,
.property-default {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 5px;
  margin-top: 10px;
}

.allowed-values > span,
.property-default > span {
  margin-right: 3px;
  color: var(--muted);
  font-size: 0.65rem;
  font-weight: 750;
  text-transform: uppercase;
}

.allowed-values code,
.property-default code,
.scalar-shape code {
  padding: 2px 5px;
  border: 1px solid var(--line);
  border-radius: 4px;
  background: #fff;
  font-size: 0.68rem;
}

.scalar-shape {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgb(255 255 255 / 52%);
}

.scalar-shape > p {
  color: #3f4c46;
}

.scalar-shape dl,
.scalar-shape dl > div {
  display: grid;
  gap: 8px;
}

.scalar-shape dl {
  margin: 0;
}

.scalar-shape dl > div {
  grid-template-columns: 80px minmax(0, 1fr);
}

.scalar-shape :is(dt, dd) {
  margin: 0;
}

.scalar-shape dt {
  color: var(--muted);
  font-size: 0.72rem;
  font-weight: 750;
}

.scalar-shape dd {
  font-size: 0.8rem;
}

.chapter-pagination {
  display: grid;
  gap: 12px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  padding-top: 30px;
}

.chapter-pagination button {
  display: grid;
  min-height: 70px;
  gap: 3px;
  padding: 12px 14px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: rgb(255 255 255 / 45%);
  text-align: left;
}

.chapter-pagination button:last-child {
  text-align: right;
}

.chapter-pagination button:hover:not(:disabled) {
  border-color: var(--line-strong);
  background: #fff;
}

.chapter-pagination button:disabled {
  cursor: default;
  opacity: 0.45;
}

.chapter-pagination span {
  color: var(--muted);
  font-size: 0.65rem;
  font-weight: 750;
  text-transform: uppercase;
}

.chapter-pagination strong {
  font-size: 0.82rem;
}

.lesson-example {
  min-width: 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: 10px;
  background: #fff;
}

.lesson-example > header {
  display: flex;
  min-height: 76px;
  align-items: center;
  justify-content: space-between;
  gap: 18px;
  padding: 16px 18px;
  border-bottom: 1px solid var(--line);
}

.lesson-example h2 {
  margin: 0;
  font-family: inherit;
  font-size: 1rem;
  font-weight: 800;
  letter-spacing: 0;
}

.example-plan {
  padding: 4px 8px;
  border-radius: 999px;
  background: var(--green-soft);
  color: #245b4c;
  font-size: 0.65rem;
  font-weight: 800;
}

.example-path {
  display: grid;
  gap: 5px;
  margin: 0;
  padding: 13px 18px;
  border-bottom: 1px solid var(--line);
}

.example-path span {
  color: var(--muted);
  font-size: 0.63rem;
  font-weight: 800;
  letter-spacing: 0.07em;
  text-transform: uppercase;
}

.example-path code {
  display: block;
  max-width: 100%;
  overflow-x: auto;
  white-space: nowrap;
}

.example-fallback {
  margin: 0;
  padding: 12px 18px;
  border-bottom: 1px solid #d9c698;
  background: var(--gold-soft);
  color: #624b1e;
  font-size: 0.74rem;
}

.example-json {
  height: 600px;
  min-width: 0;
  background: #fff;
}

.example-json > :is(.loading-message, .editor-error) {
  padding: 24px;
}

.example-json .jse-main {
  border: 0;
}

.example-json .code-panel {
  height: 100%;
  max-height: none;
  border-radius: 0;
}

.example-actions {
  display: grid;
  gap: 8px;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  padding: 14px;
  border-top: 1px solid var(--line);
}

.example-actions .button {
  min-height: 42px;
  padding: 8px 10px;
  font-size: 0.72rem;
  text-align: center;
}

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

@media (max-width: 1080px) {
  .lesson-layout {
    grid-template-columns: 210px minmax(0, 1fr);
  }

  .lesson-example {
    position: static;
    grid-column: 2;
  }
}

@media (max-width: 720px) {
  .learn-main {
    padding: 38px 0 70px;
  }

  .learn-introduction,
  .lesson-layout {
    grid-template-columns: 1fr;
  }

  .learn-introduction {
    align-items: start;
    gap: 26px;
  }

  .learn-introduction h1 {
    font-size: clamp(2.5rem, 12vw, 3.7rem);
  }

  .learn-plan-picker {
    max-width: none;
  }

  .guided-tour {
    padding: 24px 18px;
  }

  .guided-tour-heading {
    align-items: start;
    flex-direction: column;
    gap: 10px;
  }

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

  .lesson-index,
  .lesson-example {
    position: static;
  }

  .lesson-index {
    max-height: 420px;
    padding: 16px;
    border: 1px solid var(--line);
    border-radius: 8px;
    background: rgb(255 255 255 / 45%);
    overflow-y: auto;
  }

  .lesson-search {
    position: sticky;
    z-index: 2;
    top: -16px;
    padding: 0 0 12px;
    background: #f7f4ed;
  }

  .lesson-example {
    grid-column: auto;
  }

  .key-reference-heading {
    align-items: start;
    flex-direction: column;
    gap: 8px;
  }

  .example-json {
    height: 560px;
  }
}

@media (max-width: 460px) {
  .guided-tour ol,
  .chapter-pagination,
  .example-actions {
    grid-template-columns: 1fr;
  }

  .chapter-pagination button:last-child {
    text-align: left;
  }
}