/* Reading rhythm and meaningful wrapping shared by both themes. */
.main-content {
  container-type: inline-size;
  container-name: lesson;
}

/* English text can be longer than Korean labels on narrow screens. */
html[lang='en']
  .main-content
  :is(h1, h2, h3, h4, p, li, td, th, summary, button, .button, .text-link, .visual *) {
  word-break: normal;
  overflow-wrap: anywhere;
}
html[lang='en'] .main-content :is(.button, .text-link) {
  min-inline-size: 0;
  max-inline-size: 100%;
  white-space: normal;
}
html[lang='en'] .main-content :not(pre) > code {
  overflow-wrap: anywhere;
}
html[lang='en'] .analogy::before {
  content: 'Learning analogy';
}
.main-content .port-destination {
  display: block;
  font-size: 14px;
  line-height: 1.8;
}
.main-content :is(h1, h2, h3, h4) {
  text-wrap: balance;
  word-break: keep-all;
  overflow-wrap: normal;
  line-height: 1.45;
}
.main-content :is(p, li, td, th, summary, .quiz-options button, .visual-description) {
  text-wrap: pretty;
  word-break: keep-all;
  overflow-wrap: break-word;
}
.main-content:not(.home-main) {
  font-size: 16px;
  line-height: 1.95;
  letter-spacing: -0.015em;
}
.main-content:not(.home-main)
  > :is(
    .chapter-hero,
    .lesson-section,
    .source-pack,
    .callout,
    .table-wrap,
    .source-note,
    .chapter-footer
  ) {
  max-inline-size: 960px;
  margin-inline: auto;
}
.main-content:not(.home-main) .lesson-section > p:not(.source-note) {
  max-inline-size: 52rem;
}
.source-pack {
  min-inline-size: 0;
  margin-block-end: 64px;
  scroll-margin-top: 95px;
}
.source-pack > h3 {
  margin-block: 32px 14px;
  font-size: 20px;
}
.source-file {
  min-inline-size: 0;
  margin-block-start: 32px;
  padding-block-start: 24px;
  border-block-start: 1px solid var(--line);
  scroll-margin-top: 95px;
}
.source-file h4 {
  margin-block: 0 12px;
  font-size: 18px;
}
.source-pack > p,
.source-file > p {
  max-inline-size: 52rem;
}
.main-content:not(.home-main) :is(.card p, .card li, details p) {
  font-size: 15px;
  line-height: 1.95;
}
.main-content .hero-description {
  line-height: 1.95;
  text-wrap: pretty;
}
.intro-sentence {
  display: inline;
}
.section-heading {
  align-items: flex-start;
}
.section-heading h2,
.section-heading > div {
  min-inline-size: 0;
}
.section-heading .section-number {
  margin-top: 0.35em;
}
.main-content .button {
  flex-shrink: 0;
  white-space: nowrap;
  word-break: keep-all;
}
.chapter-footer {
  flex-wrap: wrap;
  justify-content: flex-start;
  align-items: flex-start;
  gap: 14px;
}
.chapter-footer > div {
  flex-basis: 100%;
  min-inline-size: 0;
  margin-bottom: 8px;
}
.chapter-footer h2 {
  max-inline-size: 38rem;
}
.chapter-footer p {
  margin-bottom: 10px;
}
.main-content .card-grid > .card {
  margin-top: 0;
}
.card-grid {
  align-items: stretch;
}
.main-content .term {
  line-height: inherit;
}

/* Keep closing punctuation with the preceding word; lists separate concepts. */
.main-content :is(p, li, td, th, summary, h1, h2, h3, h4, .visual-description) {
  line-break: strict;
}
.main-content .explanation-list {
  margin: 12px 0 20px;
  padding-inline-start: 1.45em;
  list-style: disc;
}
.main-content ol.explanation-list {
  list-style: decimal;
}
.main-content .explanation-list > li {
  padding-inline-start: 0.25em;
  margin-block: 0;
  line-height: 1.95;
}
.main-content .explanation-list > li + li {
  margin-block-start: 0.7em;
}
.main-content .explanation-list > li::marker {
  color: var(--accent-blue);
  font-size: 0.85em;
}
.main-content .explanation-list > li > strong {
  display: inline;
  margin: 0;
}
.main-content :is(.card, .callout, .analogy, details) > .explanation-list:last-child {
  margin-bottom: 0;
}
.main-content .explanation-list > li > p:last-child {
  margin-bottom: 0;
}

/* Inline examples break at authored separators, never arbitrary characters. */
.main-content :not(pre) > code {
  overflow-wrap: normal;
  word-break: keep-all;
  white-space: normal;
  padding-inline: 0.2em;
  box-decoration-break: slice;
  -webkit-box-decoration-break: slice;
  line-height: inherit;
}
.main-content pre {
  max-inline-size: 100%;
  tab-size: 2;
  text-wrap: nowrap;
}
.main-content pre code {
  white-space: pre;
  overflow-wrap: normal;
  word-break: normal;
  text-wrap: nowrap;
}
.table-wrap {
  max-inline-size: 100%;
  scrollbar-width: thin;
  scrollbar-color: #8999b5 transparent;
  overscroll-behavior-inline: contain;
}
.table-wrap table {
  min-inline-size: 600px;
  table-layout: fixed;
  line-height: 1.9;
}
.table-wrap th,
.table-wrap td {
  min-inline-size: 0;
  padding: 16px 18px;
  text-wrap: pretty;
}
.table-wrap tr > :first-child {
  inline-size: 28%;
}
.table-wrap table:has(tr > :nth-child(3)) tr > :first-child {
  inline-size: 22%;
}
.table-wrap table:has(tr > :nth-child(4)) {
  min-inline-size: 720px;
}
.table-wrap table:has(tr > :nth-child(4)) tr > :first-child {
  inline-size: auto;
}
.table-scroll-hint {
  font-size: 12px;
  color: var(--muted);
  margin: 16px 0 7px;
  line-height: 1.7;
}
.table-scroll-hint:not([hidden]) + .table-wrap {
  margin-top: 0;
}

@container lesson (max-width:700px) {
  .card-grid,
  .card-grid.three,
  .chapter-cards {
    grid-template-columns: minmax(0, 1fr);
  }
  .feature-row {
    grid-template-columns: minmax(0, 1fr);
    gap: 18px;
  }
  .chapter-card-meta {
    flex-wrap: wrap;
    row-gap: 4px;
  }
}
@container lesson (max-width:640px) {
  /* Keep each explanation visible instead of squeezing it into a narrow column. */
  .main-content .table-wrap[data-responsive='rows'] {
    overflow: visible;
  }
  .main-content .table-wrap[data-responsive='rows'] table {
    display: block;
    min-inline-size: 0;
    inline-size: 100%;
    table-layout: auto;
  }
  .main-content .table-wrap[data-responsive='rows'] caption {
    display: block;
    border-radius: 14px 14px 0 0;
  }
  .main-content .table-wrap[data-responsive='rows'] thead {
    position: absolute;
    inline-size: 1px;
    block-size: 1px;
    clip-path: inset(50%);
    overflow: hidden;
    white-space: nowrap;
  }
  .main-content .table-wrap[data-responsive='rows'] tbody {
    display: block;
  }
  .main-content .table-wrap[data-responsive='rows'] tr {
    display: block;
    border-bottom: 1px solid var(--line);
    padding: 16px 18px;
  }
  .main-content .table-wrap[data-responsive='rows'] tr:last-child {
    border-bottom: 0;
  }
  .main-content .table-wrap[data-responsive='rows'] tr > :first-child,
  .main-content .table-wrap[data-responsive='rows'] th,
  .main-content .table-wrap[data-responsive='rows'] td {
    display: block;
    inline-size: auto;
    min-inline-size: 0;
    border: 0;
    background: none;
    padding: 0;
    text-align: left;
  }
  .main-content .table-wrap[data-responsive='rows'] tbody th {
    font-size: 15px;
    margin-bottom: 12px;
  }
  .main-content .table-wrap[data-responsive='rows'] td {
    font-size: 15px;
    line-height: 1.95;
    margin-top: 12px;
  }
  .main-content .table-wrap[data-responsive='rows'] td:before {
    content: attr(data-label);
    display: block;
    color: var(--muted);
    font-size: 14px;
    font-weight: 600;
    margin-bottom: 3px;
  }
}
@media (max-width: 1100px) {
  .main-content:not(.home-main) .card-grid {
    grid-template-columns: minmax(0, 1fr);
  }
}
@media (max-width: 760px) {
  .main-content:not(.home-main) {
    padding-inline: 22px;
    font-size: 16px;
  }
  .main-content .section-heading h2 {
    font-size: 24px;
    line-height: 1.55;
  }
  .main-content .section-heading {
    gap: 11px;
  }
  .main-content :is(.card, .callout, .analogy, .quiz) {
    padding-inline: 20px;
  }
  .main-content .steps {
    padding-left: 20px;
  }
  .main-content .steps > .step {
    padding-left: 3px;
  }
  .main-content .cluster-top {
    grid-template-columns: minmax(0, 1fr);
    gap: 10px;
  }
  .main-content .cluster-connect {
    max-inline-size: none;
    padding-block: 2px;
  }
  .main-content .cluster-workers {
    grid-template-columns: minmax(0, 1fr);
  }
  .main-content .cluster-node {
    font-size: 13px;
    padding: 14px;
  }
  .main-content .cluster-node small,
  .main-content .executor {
    font-size: 12px;
  }
  .main-content .cluster-boundary {
    font-size: 10px;
    line-height: 1.8;
  }
  .main-content .visual-description {
    font-size: 14px;
    line-height: 1.9;
    min-height: 0;
  }
  .main-content .visual-header {
    align-items: flex-start;
    row-gap: 7px;
  }
  .main-content .visual-header h3 {
    flex-basis: 100%;
    font-size: 17px;
  }
  .main-content .visual-badge {
    font-size: 10px;
  }
  .main-content .visual-tabs button {
    white-space: nowrap;
  }
  .main-content .chapter-footer h2 {
    font-size: 25px;
  }
}
@media (max-width: 380px) {
  .main-content:not(.home-main) {
    padding-inline: 17px;
  }
  .main-content .chapter-hero h1 {
    font-size: 30px;
  }
  .main-content .section-heading h2 {
    font-size: 22px;
  }
}
/* Teaching text stays readable inside tables and diagrams on every viewport. */
.main-content .table-wrap :is(table, th, td) {
  font-size: 15px;
}
.main-content .table-wrap caption {
  font-size: 14px;
  line-height: 1.8;
}
.main-content .table-wrap :is(th, td) code {
  font-size: 14px;
}
.main-content .visual .visual-header {
  flex-wrap: wrap;
  align-items: flex-start;
}
.main-content .visual .visual-header h3 {
  font-size: 19px;
}
.main-content .visual .visual-badge {
  font-size: 12px;
  white-space: normal;
}
.main-content .visual .visual-tabs button {
  font-size: 14px;
  min-height: 42px;
  white-space: normal;
  text-align: left;
}
.main-content .visual .visual-description {
  font-size: 16px;
  line-height: 1.95;
  min-height: 0;
}
.main-content .visual :is(.flow-node strong, .cluster-node) {
  font-size: 16px;
  min-inline-size: 0;
}
.main-content
  .visual
  :is(
    .flow-node small,
    .cluster-node small,
    .cluster-boundary,
    .cluster-connect,
    .executor,
    .port-bridge,
    .cluster-flow,
    .partition-block small,
    .partition-result,
    .sum-result small,
    .port-route code
  ) {
  font-size: 14px;
  line-height: 1.8;
  word-break: keep-all;
  text-wrap: pretty;
}
.main-content .visual .cluster-connect {
  max-inline-size: 130px;
}
.main-content .visual :is(.cluster-top, .cluster-workers, .cluster-flow) {
  max-inline-size: none;
}
.main-content .visual .partition-block {
  min-inline-size: 0;
}
.main-content .visual .partition-block strong {
  font-size: 22px;
}
.main-content .visual .flow-node {
  min-inline-size: 0;
}
@container lesson (max-width:800px) {
  .main-content .visual :is(.cluster-top, .cluster-workers, .port-route) {
    grid-template-columns: minmax(0, 1fr);
  }
  .main-content .visual .cluster-connect {
    max-inline-size: none;
  }
  .main-content .visual .flow-line {
    display: grid;
    grid-template-columns: minmax(0, 1fr);
  }
  .main-content .visual .flow-arrow {
    display: block;
    justify-self: center;
    transform: rotate(90deg);
    line-height: 1;
  }
  .main-content .visual .partition-grid {
    grid-template-columns: repeat(2, minmax(0, 1fr));
  }
}
@container lesson (max-width:360px) {
  .main-content .visual .partition-grid {
    grid-template-columns: minmax(0, 1fr);
  }
  .main-content .visual .cluster-canvas {
    padding: 12px;
  }
}
@media print {
  .main-content {
    container-type: normal;
  }
  .main-content .table-wrap table {
    min-inline-size: 0;
    table-layout: auto;
  }
  .table-scroll-hint {
    display: none !important;
  }
  .main-content pre,
  .main-content pre code {
    white-space: pre-wrap;
    overflow-wrap: anywhere;
    text-wrap: wrap;
  }
}

/* Short, named reading blocks and locally bundled teaching illustrations. */
.main-content .lesson-section > h3 {
  margin-block: 34px 12px;
  padding-block-start: 20px;
  border-block-start: 1px solid var(--line);
  font-size: 21px;
  line-height: 1.55;
}
.main-content .lesson-section > .explanation-list {
  max-inline-size: 52rem;
}
.main-content .steps > .step + .step {
  border-block-start: 1px solid var(--line);
  padding-block-start: 22px;
}
.main-content .lesson-section .lesson-figure {
  max-inline-size: 720px;
  margin: 26px auto 30px;
  border: 1px solid var(--line);
  border-radius: 16px;
  overflow: hidden;
  background: var(--surface, #fff);
}
.main-content .lesson-figure img {
  display: block;
  inline-size: 100%;
  block-size: auto;
  aspect-ratio: 3/2;
  object-fit: contain;
  background: #eae8e3;
}
.main-content .lesson-figure figcaption {
  margin: 0;
  padding: 16px 20px;
  font-size: 14px;
  line-height: 1.8;
  color: var(--muted);
  word-break: keep-all;
  overflow-wrap: break-word;
}
.main-content .lesson-figure figcaption strong {
  color: var(--ink);
}
@media (max-width: 760px) {
  .main-content .lesson-section > h3 {
    font-size: 20px;
    margin-block-start: 28px;
    padding-block-start: 18px;
  }
  .main-content .lesson-figure figcaption {
    padding: 14px 16px;
  }
}
@media print {
  .main-content .lesson-section .lesson-figure {
    max-inline-size: 110mm;
    break-inside: avoid;
    background: white;
  }
}

.main-content .analogy[data-labelled]::before {
  display: none;
}
/* Chapter learning routes, source group labels, and original UI evidence. */
.main-content > .learning-route,
.main-content > .lesson-part {
  max-inline-size: 960px;
  margin-inline: auto;
}
.learning-route {
  margin-block: 32px 26px;
  padding: 24px;
  border: 1px solid var(--line);
  border-radius: 18px;
  background: var(--surface);
}
.learning-route ol {
  list-style: none;
  padding: 0;
  margin: 14px 0 20px;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 18px;
}
.learning-route li {
  margin: 0;
  min-inline-size: 0;
}
.learning-route a {
  display: block;
  padding: 12px 0;
  text-decoration: none;
  border-block-end: 2px solid var(--accent-blue);
  height: 100%;
}
.learning-route a strong,
.learning-route a span {
  display: block;
}
.learning-route a span {
  color: var(--muted);
  font-size: 14px;
  margin-top: 6px;
}
.learning-route > p:last-child {
  margin: 0;
  font-size: 15px;
}
.main-content > .lesson-part {
  --part-accent: var(--accent-blue);
  --part-tint: var(--tint-blue);
  display: grid;
  grid-template-columns: minmax(0, 1fr) 180px;
  align-items: center;
  gap: 28px;
  margin-block: 96px 40px;
  padding: 32px;
  border: 1px solid var(--line);
  border-block-start: 4px solid var(--part-accent);
  border-radius: 20px;
  background: var(--part-tint);
}
.lesson-part[data-part='B'] {
  --part-accent: var(--accent-purple);
  --part-tint: var(--tint-purple);
}
.lesson-part[data-part='C'] {
  --part-accent: var(--accent-teal);
  --part-tint: var(--tint-teal);
}
.lesson-part .part-copy {
  min-inline-size: 0;
}
.main-content .lesson-part .part-title {
  display: flex;
  align-items: flex-start;
  gap: 16px;
  margin: 0 0 18px;
  font-size: 38px;
  font-weight: 750;
  line-height: 1.35;
  letter-spacing: -0.04em;
  color: var(--ink);
}
.part-title > span:last-child {
  min-inline-size: 0;
}
.part-letter {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  inline-size: 48px;
  block-size: 48px;
  border: 1px solid currentColor;
  border-radius: 12px;
  color: var(--part-accent);
  font-size: 28px;
  letter-spacing: 0;
}
.lesson-part .part-art {
  display: block;
  inline-size: 180px;
  block-size: 180px;
  object-fit: contain;
}
.main-content > .lesson-part p {
  margin: 0;
  max-inline-size: 38rem;
}
.toc-group {
  font-size: 12px;
  font-weight: 700;
  color: var(--muted);
  margin: 22px 0 7px;
  padding-inline: 14px;
}
.toc-group:first-child {
  margin-top: 10px;
}
.main-content .source-figure {
  margin: 26px 0;
  border: 1px solid var(--line);
  border-radius: 14px;
  overflow: hidden;
}
.main-content .source-figure img {
  display: block;
  inline-size: 100%;
  block-size: auto;
  background: #fff;
}
.main-content .source-figure figcaption {
  margin: 0;
  padding: 16px 20px;
  font-size: 14px;
  line-height: 1.9;
  color: var(--muted);
}
@container lesson (max-width:700px) {
  .learning-route ol {
    grid-template-columns: minmax(0, 1fr);
    gap: 6px;
  }
}
@media (max-width: 760px) {
  .learning-route {
    padding: 20px;
  }
  .main-content .source-figure figcaption {
    padding: 14px 16px;
  }
}
/* Clear transitions throughout lessons and the practice guide. */
@media screen {
  .main-content:not(.home-main) .section-heading h2 {
    font-size: 34px;
    line-height: 1.4;
  }
  .main-content:not(.home-main) .lesson-section > .section-heading {
    padding-block-start: 28px;
    border-block-start: 2px solid var(--line);
    margin-block-end: 28px;
    gap: 18px;
  }
  .main-content:not(.home-main) .lesson-part + .lesson-section > .section-heading {
    padding-block-start: 0;
    border-block-start: 0;
  }
  .main-content:not(.home-main) .section-number {
    inline-size: 46px;
    block-size: 46px;
    margin-top: 0;
    font-size: 17px;
    font-weight: 750;
    background: var(--tint-blue);
    color: var(--accent-blue);
  }
  .main-content:not(.home-main) :is(.lesson-section, .source-pack) > h3 {
    margin-block: 52px 18px;
    padding-block-start: 26px;
    border-block-start: 1px solid var(--line);
    font-size: 27px;
    font-weight: 750;
    line-height: 1.45;
    letter-spacing: -0.035em;
  }
  .main-content:not(.home-main) .source-file {
    margin-block-start: 48px;
    padding-block-start: 30px;
  }
  .main-content:not(.home-main) .source-file > h4 {
    margin-block-end: 18px;
    font-size: 24px;
    line-height: 1.5;
  }
  .main-content:not(.home-main) .steps > .step > h3 {
    margin-block-end: 16px;
    font-size: 24px;
    font-weight: 750;
    line-height: 1.5;
  }
  .main-content:not(.home-main) .source-file > h4 code {
    font-size: 0.88em;
  }
}
@container lesson (max-width:700px) {
  .main-content > .lesson-part {
    grid-template-columns: minmax(0, 1fr);
    gap: 0;
    margin-block: 64px 32px;
    padding: 24px;
  }
  .main-content .lesson-part .part-title {
    font-size: 30px;
    gap: 12px;
    margin-bottom: 16px;
  }
  .part-letter {
    inline-size: 38px;
    block-size: 38px;
    border-radius: 10px;
    font-size: 23px;
  }
  .lesson-part .part-art {
    grid-row: 1;
    inline-size: 104px;
    block-size: 104px;
    margin-block-end: 12px;
  }
  .main-content:not(.home-main) .section-heading h2 {
    font-size: 28px;
  }
  .main-content:not(.home-main) .lesson-section > .section-heading {
    gap: 12px;
  }
  .main-content:not(.home-main) .section-number {
    inline-size: 38px;
    block-size: 38px;
    font-size: 15px;
  }
  .main-content:not(.home-main) :is(.lesson-section, .source-pack) > h3 {
    margin-block: 42px 16px;
    padding-block-start: 22px;
    font-size: 24px;
  }
  .main-content:not(.home-main) .source-file > h4 {
    font-size: 22px;
  }
  .main-content:not(.home-main) .steps > .step > h3 {
    font-size: 22px;
  }
}
@media screen and (max-width: 380px) {
  .main-content > .lesson-part {
    padding: 20px;
  }
  .main-content .lesson-part .part-title {
    font-size: 27px;
  }
  .main-content:not(.home-main) .section-heading h2 {
    font-size: 26px;
  }
  .main-content:not(.home-main) :is(.lesson-section, .source-pack) > h3 {
    font-size: 23px;
  }
}
@media print {
  .learning-route {
    background: white;
  }
  .main-content > .lesson-part {
    break-after: avoid;
    display: block;
    margin-block: 24pt 16pt;
    padding: 16pt 0 0;
    border-inline: 0;
    border-block-end: 0;
    border-radius: 0;
    background: white;
  }
  .main-content .lesson-part .part-title {
    font-size: 22pt;
  }
  .lesson-part .part-art {
    display: none;
  }
  .main-content .source-figure {
    break-inside: avoid;
  }
  .main-content .source-figure img {
    max-block-size: 100mm;
    object-fit: contain;
  }
}

/* Native navigation remains available without scripts and wraps on narrow screens. */
.course-return {
  display: flex;
  flex-wrap: wrap;
  gap: 8px 20px;
  margin: 0 0 24px;
}
.course-return a {
  display: inline-flex;
  align-items: center;
  min-height: 44px;
  padding: 4px 0;
  color: var(--blue);
  text-decoration: underline;
  text-underline-offset: 4px;
}
.course-return a:focus-visible {
  outline: 3px solid currentColor;
  outline-offset: 4px;
  border-radius: 4px;
}