:root {
  color-scheme: light;
  --site-bg: #f6f9fc;
  --site-paper: #ffffff;
  --site-sidebar: #f1f6fb;
  --site-tool: #f7f9fc;
  --site-header: #173a5e;
  --site-header-soft: #e9f1f8;
  --site-text: #18324d;
  --site-muted: #60758b;
  --site-faint: #7b8da0;
  --site-line: rgb(24 50 77 / 10%);
  --site-line-strong: rgb(24 50 77 / 18%);
  --site-blue: #2b72b9;
  --site-blue-hover: #225f9c;
  --site-blue-soft: #e7f0fa;
  --site-audio: #e86f68;
  --site-audio-hover: #d85e58;
  --site-audio-soft: #fdeae8;
  --site-width: 1600px;
  --site-gutter: clamp(22px, 4vw, 52px);
  --site-font:
    'Geist Sans', 'Noto Sans SC', 'Noto Sans JP', 'Hiragino Sans',
    'PingFang SC', system-ui, sans-serif;
}

* {
  box-sizing: border-box;
}

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

body {
  min-width: 320px;
  margin: 0;
  color: var(--site-text);
  background: var(--site-bg);
  font-family: var(--site-font);
  font-size: 16px;
  line-height: 1.65;
  -webkit-font-smoothing: antialiased;
}

a {
  color: inherit;
  text-decoration: none;
}

a:hover {
  color: var(--site-blue);
}

svg {
  width: 22px;
  height: 22px;
  flex: 0 0 auto;
}

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

.skip-link {
  position: fixed;
  z-index: 100;
  top: 8px;
  left: 8px;
  padding: 8px 12px;
  color: #ffffff;
  background: var(--site-audio);
  transform: translateY(-160%);
}

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

:focus-visible {
  outline: 2px solid var(--site-blue);
  outline-offset: 3px;
}

.site-header,
.site-footer,
.section-pad,
.page-shell,
.article-shell {
  width: min(100%, var(--site-width));
  margin-inline: auto;
  padding-inline: var(--site-gutter);
}

.site-header {
  position: relative;
  z-index: 10;
  display: flex;
  min-height: 76px;
  align-items: center;
  justify-content: space-between;
  color: var(--site-text);
  background: var(--site-header-soft);
  border-bottom: 1px solid var(--site-line);
  box-shadow: 0 0 0 100vmax var(--site-header-soft);
  clip-path: inset(0 -100vmax);
}

.site-header-dark {
  color: var(--site-paper);
  background: var(--site-header);
  border-bottom-color: rgb(255 255 255 / 11%);
  box-shadow: 0 0 0 100vmax var(--site-header);
}

.brand {
  display: inline-flex;
  min-width: 142px;
  flex-direction: column;
  justify-content: center;
  color: inherit;
  line-height: 1.15;
}

.brand strong {
  font-size: 23px;
  font-weight: 720;
  letter-spacing: 0.04em;
}

.brand span {
  margin-top: 4px;
  color: var(--site-muted);
  font-size: 13px;
  letter-spacing: 0.02em;
}

.site-header nav,
.site-footer nav {
  display: flex;
  align-items: center;
  gap: clamp(22px, 4vw, 52px);
}

.site-header nav a {
  position: relative;
  padding: 26px 0 24px;
  font-size: 15px;
  font-weight: 540;
  color: var(--site-muted);
}

.site-header nav a[aria-current='page'] {
  color: var(--site-text);
}

.site-header-dark .brand span {
  color: rgb(248 251 255 / 66%);
}

.site-header-dark nav a {
  color: rgb(248 251 255 / 82%);
}

.site-header-dark nav a[aria-current='page'] {
  color: var(--site-paper);
}

.site-header nav a[aria-current='page']::after {
  position: absolute;
  right: 0;
  bottom: -1px;
  left: 0;
  height: 2px;
  background: var(--site-audio);
  content: '';
}

.hero {
  position: relative;
  display: grid;
  min-height: 520px;
  align-items: center;
  gap: clamp(40px, 4vw, 64px);
  grid-template-columns: minmax(500px, 0.88fr) minmax(620px, 1.12fr);
  border-bottom: 1px solid var(--site-line);
  isolation: isolate;
  overflow: hidden;
}

.hero::before,
.hero::after {
  position: absolute;
  z-index: -1;
  border-radius: 50%;
  content: '';
  pointer-events: none;
}

.hero::before {
  top: 70px;
  right: -120px;
  width: 760px;
  height: 540px;
  background: rgb(219 233 247 / 38%);
}

.hero::after {
  right: -8%;
  bottom: -305px;
  left: -18%;
  height: 430px;
  background: #edf4fb;
}

.home .hero {
  min-height: calc(100svh - 202px);
}

.hero-copy {
  position: relative;
  z-index: 1;
  padding-block: 54px;
}

.hero h1 {
  max-width: 650px;
  margin: 0;
  font-size: clamp(42px, 4vw, 56px);
  font-weight: 730;
  letter-spacing: -0.045em;
  line-height: 1.14;
}

.hero-copy > p {
  max-width: 520px;
  margin: 32px 0 0;
  color: var(--site-muted);
  font-size: clamp(20px, 2vw, 26px);
  line-height: 1.65;
}

.actions {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 14px;
  margin-top: 38px;
}

[hidden] {
  display: none !important;
}

.continue-action {
  min-height: 60px;
  padding-block: 9px;
}

.continue-action > span {
  display: flex;
  align-items: flex-start;
  flex-direction: column;
  gap: 4px;
  text-align: left;
}

.continue-action strong {
  font-size: 16px;
  line-height: 1;
}

.continue-action small {
  color: rgb(255 255 255 / 82%);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.2;
}

.guide-action {
  display: inline-flex;
  min-height: 50px;
  align-items: center;
  gap: 8px;
  padding-inline: 10px;
  color: var(--site-blue);
  font-size: 15px;
  font-weight: 620;
}

.guide-action svg {
  width: 17px;
  height: 17px;
  transition: transform 150ms ease;
}

.guide-action:hover svg {
  transform: translateX(3px);
}

.button {
  display: inline-flex;
  min-height: 50px;
  align-items: center;
  justify-content: center;
  gap: 10px;
  padding: 0 30px;
  border: 1px solid var(--site-blue);
  border-radius: 7px;
  font-size: 16px;
  font-weight: 620;
  line-height: 1;
  transition:
    color 160ms ease,
    background 160ms ease,
    border-color 160ms ease;
}

.button svg {
  width: 18px;
  height: 18px;
}

.button.primary {
  color: var(--site-paper);
  background: var(--site-audio);
  border-color: var(--site-audio);
}

.button.primary:hover {
  color: var(--site-paper);
  background: var(--site-audio-hover);
  border-color: var(--site-audio-hover);
}

.button.secondary {
  color: var(--site-blue);
  background: var(--site-paper);
}

.button.secondary:hover {
  background: var(--site-blue-soft);
}

.reader-preview {
  position: relative;
  display: block;
  margin: 0;
  overflow: hidden;
  border: 1px solid rgb(43 114 185 / 24%);
  border-radius: 14px;
  background: var(--site-paper);
  box-shadow: 0 22px 54px rgb(24 50 77 / 14%);
  aspect-ratio: 1.72;
}

.reader-preview::after {
  position: absolute;
  inset: 0;
  border: 1px solid rgb(255 255 255 / 78%);
  border-radius: inherit;
  content: '';
  pointer-events: none;
}

.reader-preview img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  object-position: top left;
}

.textbook-strip,
.workflow,
.index-section,
.final-cta {
  border-bottom: 1px solid var(--site-line);
}

.textbook-strip,
.workflow,
.index-section {
  padding-block: 38px;
}

.textbook-strip h2,
.workflow h2,
.index-section h2,
.final-cta h2,
.content-band h2,
.study-and-guide h2 {
  margin: 0;
  font-size: clamp(26px, 2.6vw, 36px);
  font-weight: 690;
  letter-spacing: -0.03em;
  line-height: 1.25;
}

.workflow {
  padding-top: 64px;
  padding-bottom: 56px;
}

.workflow ol,
.numbered-flow {
  display: grid;
  margin: 34px 0 0;
  padding: 0;
  list-style: none;
  grid-template-columns: repeat(3, 1fr);
}

.workflow li,
.numbered-flow li {
  position: relative;
  display: flex;
  gap: 22px;
  padding-right: 58px;
}

.workflow li:not(:last-child)::after {
  position: absolute;
  top: 18px;
  right: 24px;
  width: 78px;
  height: 1px;
  background: var(--site-line-strong);
  content: '';
  transform: translateX(50%);
}

.workflow li > b {
  color: var(--site-audio);
  font-size: 38px;
  font-weight: 690;
  line-height: 1;
}

.workflow li span,
.numbered-flow li span {
  display: flex;
  flex-direction: column;
}

.workflow li strong,
.numbered-flow li strong {
  font-size: 18px;
  line-height: 1.25;
}

.workflow li small,
.numbered-flow li small {
  margin-top: 8px;
  color: var(--site-muted);
  font-size: 14px;
  line-height: 1.6;
}

.section-heading {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 24px;
}

.section-heading a {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--site-blue);
  font-size: 14px;
  font-weight: 600;
}

.section-heading a svg {
  width: 17px;
  height: 17px;
}

.rule-list {
  margin-top: 26px;
  border-top: 1px solid var(--site-line-strong);
}

.rule-list.large {
  margin-top: 54px;
}

.book-row,
.guide-row {
  display: grid;
  min-height: 82px;
  align-items: center;
  gap: 22px;
  border-bottom: 1px solid var(--site-line);
}

.book-row {
  grid-template-columns: 130px 250px minmax(260px, 1fr) 22px;
}

.book-row > span:nth-child(2) {
  display: flex;
  flex-direction: column;
}

.book-row strong,
.guide-row strong {
  font-size: 17px;
  font-weight: 620;
}

.book-row small {
  margin-top: 2px;
  color: var(--site-muted);
  font-size: 12px;
}

.book-mark {
  display: flex;
  align-items: baseline;
  gap: 9px;
  color: var(--book-color);
}

.book-mark b {
  font-size: 19px;
}

.book-mark small {
  color: var(--site-muted);
}

.book-summary,
.guide-row > span {
  color: var(--site-muted);
  font-size: 14px;
}

.book-row > svg,
.guide-row > svg:last-child,
.lesson-row > svg,
.feature-index > a > svg {
  color: var(--site-blue);
}

.guide-row {
  grid-template-columns: 24px minmax(230px, 0.85fr) minmax(340px, 1.4fr) 22px;
}

.guide-row > svg:first-child {
  color: var(--site-blue);
}

.final-cta {
  padding-top: 50px;
  padding-bottom: 58px;
  text-align: center;
}

.final-cta .button {
  margin-top: 22px;
}

.site-footer {
  display: grid;
  min-height: 126px;
  align-items: center;
  gap: 28px;
  grid-template-columns: 180px minmax(0, 1fr) auto;
  border-top: 1px solid var(--site-line);
  background: rgb(255 255 255 / 56%);
}

.site-footer nav {
  justify-content: center;
  gap: 26px;
}

.site-footer nav a,
.site-footer p {
  color: var(--site-muted);
  font-size: 13px;
}

.site-footer p {
  margin: 0;
  white-space: nowrap;
}

.site-footer .brand span {
  color: var(--site-muted);
}

.page-shell,
.article-shell {
  min-height: calc(100vh - 202px);
  padding-top: 34px;
  padding-bottom: 76px;
}

.breadcrumb {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  color: var(--site-muted);
  font-size: 14px;
}

.breadcrumb a {
  color: var(--site-blue);
}

.breadcrumb i {
  color: var(--site-faint);
  font-style: normal;
}

.page-intro,
.book-intro {
  padding: 48px 0 30px;
}

.page-intro {
  max-width: 850px;
}

.page-intro h1,
.book-intro h1,
.lesson-intro h1,
.feature-intro h1,
.article-shell article > header h1,
.not-found h1 {
  margin: 0;
  font-size: clamp(42px, 5vw, 66px);
  font-weight: 720;
  letter-spacing: -0.045em;
  line-height: 1.15;
}

.page-intro > p,
.book-intro p,
.lesson-intro > p:last-of-type,
.feature-intro p {
  margin: 20px 0 0;
  color: var(--site-muted);
  font-size: 19px;
  line-height: 1.75;
}

.page-intro .button {
  margin-top: 28px;
}

.content-band,
.prose,
.contact-panel,
.faq-list {
  margin-top: 44px;
  padding-top: 40px;
  border-top: 1px solid var(--site-line-strong);
}

.columns {
  display: grid;
  gap: 64px;
  margin-top: 28px;
  grid-template-columns: repeat(2, 1fr);
}

.columns h3,
.prose h2,
.contact-panel h2 {
  margin: 0 0 12px;
  font-size: 21px;
}

.columns p,
.prose p,
.prose li,
.contact-panel li {
  color: var(--site-muted);
}

.numbered-flow li > b {
  display: grid;
  width: 36px;
  height: 36px;
  flex: 0 0 auto;
  place-items: center;
  color: var(--site-blue);
  border: 1px solid var(--site-blue);
  border-radius: 50%;
  font-size: 15px;
}

.directory-intro {
  padding-bottom: 34px;
}

.course-directory {
  display: grid;
  gap: 14px;
}

.course-group {
  overflow: hidden;
  border: 1px solid var(--site-line-strong);
  border-radius: 12px;
  background: rgb(255 255 255 / 82%);
  box-shadow: 0 8px 24px rgb(24 50 77 / 5%);
}

.course-summary {
  position: relative;
  display: grid;
  min-height: 112px;
  cursor: pointer;
  align-items: center;
  gap: 22px;
  padding: 16px 64px 16px 20px;
  grid-template-columns: 56px minmax(0, 1fr) auto;
  list-style: none;
}

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

.course-summary::after {
  position: absolute;
  top: 50%;
  right: 26px;
  width: 9px;
  height: 9px;
  border-right: 1.5px solid var(--site-blue);
  border-bottom: 1.5px solid var(--site-blue);
  content: '';
  transform: translateY(-65%) rotate(45deg);
  transition: transform 150ms ease;
}

.course-group[open] .course-summary::after {
  transform: translateY(-25%) rotate(225deg);
}

.course-group[open] .course-summary {
  border-bottom: 1px solid var(--site-line);
  background: #edf4fa;
}

.course-summary > img {
  width: 56px;
  height: 80px;
  object-fit: contain;
  border: 1px solid var(--site-line);
  background: var(--site-paper);
}

.course-summary > span {
  display: flex;
  min-width: 0;
  flex-direction: column;
}

.course-summary small,
.course-summary > span > span,
.course-summary > b {
  color: var(--site-muted);
  font-size: 13px;
  font-weight: 520;
}

.course-summary strong {
  margin: 3px 0 2px;
  font-size: 20px;
}

.course-summary > b {
  padding: 5px 10px;
  border-radius: 999px;
  background: var(--site-blue-soft);
  color: var(--site-blue);
}

.course-lessons {
  margin: 0;
  padding-inline: 22px;
  border-top: 0;
}

.course-about {
  display: flex;
  justify-content: flex-end;
  padding: 14px 22px 18px;
}

.course-about a {
  display: inline-flex;
  align-items: center;
  gap: 7px;
  color: var(--site-blue);
  font-size: 13px;
  font-weight: 620;
}

.course-about svg {
  width: 16px;
  height: 16px;
}

.book-intro {
  display: flex;
  align-items: end;
  justify-content: space-between;
  gap: 48px;
}

.book-intro > div {
  max-width: 850px;
}

.lesson-table {
  margin-top: 20px;
  border-top: 1px solid var(--site-line-strong);
}

.lesson-head,
.lesson-row {
  display: grid;
  min-height: 56px;
  align-items: center;
  gap: 20px;
  grid-template-columns: 106px minmax(280px, 1fr) 100px 100px 100px 22px;
  border-bottom: 1px solid var(--site-line);
}

.lesson-head {
  min-height: 46px;
  color: var(--site-muted);
  font-size: 12px;
  font-weight: 600;
  letter-spacing: 0.04em;
}

.lesson-row > span,
.lesson-row small {
  color: var(--site-muted);
  font-size: 14px;
}

.lesson-row strong {
  color: var(--site-blue);
  font-size: 16px;
  font-weight: 520;
}

.study-and-guide {
  display: grid;
  gap: 48px;
  margin-top: 42px;
  padding-top: 36px;
  grid-template-columns: 1.05fr 0.95fr;
  border-top: 1px solid var(--site-line-strong);
}

.study-and-guide > div {
  padding-right: 48px;
  border-right: 1px solid var(--site-line);
}

.study-and-guide p {
  color: var(--site-muted);
}

.compact-flow {
  display: flex;
  flex-wrap: wrap;
  align-items: center;
  gap: 12px;
  margin: 25px 0 0;
  padding: 0;
  list-style: none;
}

.compact-flow li {
  display: flex;
  align-items: center;
  gap: 8px;
}

.compact-flow li:not(:last-child)::after {
  margin-left: 5px;
  color: var(--site-faint);
  content: '→';
}

.compact-flow b {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  color: var(--site-blue);
  border: 1px solid var(--site-blue);
  border-radius: 50%;
  font-size: 13px;
}

.related-guide {
  display: grid;
  min-height: 120px;
  align-items: center;
  gap: 20px;
  grid-template-columns: 40px minmax(0, 1fr) 22px;
}

.related-guide > svg {
  color: var(--site-blue);
}

.related-guide > svg:first-child {
  width: 38px;
  height: 38px;
}

.related-guide span {
  display: flex;
  flex-direction: column;
}

.related-guide small {
  color: var(--site-muted);
}

.related-guide strong {
  margin-top: 6px;
  color: var(--site-blue);
  font-size: 18px;
}

.lesson-intro {
  max-width: 930px;
  padding: 50px 0 38px;
}

.lesson-intro > p:first-child,
.article-shell article > header > p,
.guide-index > a > span {
  margin: 0 0 14px;
  color: var(--site-blue);
  font-size: 13px;
  font-weight: 650;
  letter-spacing: 0.06em;
}

.lesson-intro .button {
  margin-top: 30px;
}

.lesson-facts {
  display: grid;
  border-top: 1px solid var(--site-line-strong);
  border-bottom: 1px solid var(--site-line);
  grid-template-columns: repeat(4, 1fr);
}

.lesson-facts div {
  display: flex;
  min-height: 104px;
  flex-direction: column;
  justify-content: center;
  padding: 18px 24px;
  border-right: 1px solid var(--site-line);
}

.lesson-facts div:last-child {
  border-right: 0;
}

.lesson-facts strong {
  font-size: 27px;
}

.lesson-facts span,
.available-docs {
  color: var(--site-muted);
  font-size: 14px;
}

.lesson-neighbors {
  display: grid;
  margin-top: 44px;
  grid-template-columns: repeat(2, 1fr);
  border-top: 1px solid var(--site-line-strong);
  border-bottom: 1px solid var(--site-line);
}

.lesson-neighbors a {
  display: flex;
  min-height: 88px;
  flex-direction: column;
  justify-content: center;
  padding: 18px 24px;
}

.lesson-neighbors a + a,
.lesson-neighbors span + a {
  align-items: flex-end;
  border-left: 1px solid var(--site-line);
  text-align: right;
}

.lesson-neighbors small {
  color: var(--site-muted);
}

.lesson-neighbors strong {
  margin-top: 4px;
  color: var(--site-blue);
  font-size: 15px;
}

.check-list {
  display: grid;
  gap: 0;
  margin: 24px 0 0;
  padding: 0;
  list-style: none;
  grid-template-columns: repeat(3, 1fr);
  border-top: 1px solid var(--site-line);
}

.check-list li {
  position: relative;
  min-height: 74px;
  padding: 22px 28px 22px 24px;
  border-right: 1px solid var(--site-line);
  border-bottom: 1px solid var(--site-line);
}

.check-list li:last-child {
  border-right: 0;
}

.check-list li::before {
  margin-right: 10px;
  color: var(--site-blue);
  content: '✓';
  font-weight: 700;
}

.guide-index,
.feature-index {
  margin-top: 36px;
  border-top: 1px solid var(--site-line-strong);
}

.guide-index > a {
  position: relative;
  display: grid;
  min-height: 118px;
  align-items: center;
  gap: 18px 36px;
  padding: 24px 54px 24px 0;
  grid-template-columns: 135px minmax(260px, 0.8fr) minmax(320px, 1.2fr);
  border-bottom: 1px solid var(--site-line);
}

.guide-index > a strong {
  font-size: 19px;
}

.guide-index > a p {
  margin: 0;
  color: var(--site-muted);
}

.guide-index > a svg {
  position: absolute;
  top: 50%;
  right: 0;
  color: var(--site-blue);
  transform: translateY(-50%);
}

.article-shell article {
  width: min(100%, 820px);
  margin: 48px auto 0;
}

.article-shell article > header {
  padding-bottom: 40px;
  border-bottom: 1px solid var(--site-line-strong);
}

.article-shell article > header h1 {
  font-size: clamp(40px, 4.8vw, 62px);
}

.article-meta {
  display: flex;
  gap: 16px;
  margin-top: 24px;
  color: var(--site-faint);
  font-size: 13px;
}

.article-meta span:not(:last-child)::after {
  margin-left: 16px;
  color: var(--site-line-strong);
  content: '/';
}

.lead {
  margin: 30px 0 0;
  color: var(--site-muted);
  font-size: 21px;
  line-height: 1.75;
}

.article-shell article > section {
  padding-top: 34px;
}

.article-shell article h2 {
  margin: 0 0 14px;
  font-size: 28px;
  letter-spacing: -0.02em;
}

.article-shell article section p,
.article-shell article section li {
  color: var(--site-text);
  font-size: 17px;
  line-height: 1.9;
}

.article-shell article ul,
.prose ul,
.contact-panel ul {
  padding-left: 1.3em;
}

.article-next {
  margin-top: 52px;
  padding: 34px;
  border: 1px solid var(--site-line-strong);
  border-radius: 7px;
}

.article-next strong {
  font-size: 22px;
}

.article-next p {
  margin: 8px 0 20px;
  color: var(--site-muted);
}

.feature-index > a {
  display: grid;
  min-height: 120px;
  align-items: center;
  gap: 28px;
  grid-template-columns: 72px minmax(0, 1fr) 22px;
  border-bottom: 1px solid var(--site-line);
}

.feature-index > a > b,
.feature-intro > b {
  color: var(--site-blue);
  font-size: 34px;
  font-weight: 660;
}

.feature-index strong {
  font-size: 21px;
}

.feature-index p {
  margin: 4px 0 0;
  color: var(--site-muted);
}

.feature-intro {
  display: grid;
  gap: 34px;
  padding: 54px 0 38px;
  grid-template-columns: 80px minmax(0, 820px);
}

.feature-intro .button {
  margin-top: 26px;
}

.faq-list details {
  border-bottom: 1px solid var(--site-line);
}

.faq-list summary {
  padding: 22px 0;
  cursor: pointer;
  font-size: 18px;
  font-weight: 620;
}

.faq-list details p {
  max-width: 800px;
  margin: -4px 0 26px;
  color: var(--site-muted);
}

.prose {
  max-width: 840px;
}

.prose h2:not(:first-child) {
  margin-top: 38px;
}

.prose p,
.prose li {
  font-size: 17px;
  line-height: 1.9;
}

.contact-panel {
  display: grid;
  gap: 60px;
  grid-template-columns: 0.7fr 1.3fr;
}

.contact-panel a {
  color: var(--site-blue);
  font-size: 22px;
  font-weight: 600;
}

.not-found {
  display: flex;
  min-height: 620px;
  align-items: center;
  flex-direction: column;
  justify-content: center;
  text-align: center;
}

.not-found > p {
  margin: 0 0 10px;
  color: var(--site-blue);
  font-size: 30px;
  font-weight: 700;
}

.not-found > span {
  margin-top: 18px;
  color: var(--site-muted);
}

@media (max-width: 1050px) {
  .hero {
    min-height: auto;
    padding-top: 64px;
    padding-bottom: 64px;
    grid-template-columns: 1fr;
  }

  .home .hero {
    min-height: auto;
  }

  .hero-copy {
    padding: 0;
  }

  .reader-preview {
    max-width: 880px;
  }

  .book-row {
    grid-template-columns: 120px minmax(220px, 0.8fr) minmax(260px, 1.2fr) 22px;
  }

  .lesson-head,
  .lesson-row {
    grid-template-columns: 90px minmax(250px, 1fr) 90px 90px 22px;
  }

  .lesson-head span:nth-child(5),
  .lesson-row small:nth-child(5) {
    display: none;
  }

  .guide-index > a {
    grid-template-columns: 110px minmax(230px, 0.8fr) minmax(260px, 1.2fr);
  }

  .site-footer {
    grid-template-columns: 160px 1fr;
  }

  .site-footer p {
    display: none;
  }
}

@media (max-width: 760px) {
  .site-header {
    min-height: 64px;
    padding-top: 10px;
    padding-bottom: 10px;
  }

  .brand strong {
    font-size: 19px;
  }

  .brand span {
    font-size: 11px;
  }

  .site-header nav {
    gap: 15px;
  }

  .site-header nav a {
    padding: 14px 0;
    font-size: 13px;
  }

  .site-header nav a:nth-child(3),
  .site-header nav a:nth-child(4) {
    display: none;
  }

  .hero {
    gap: 40px;
    padding-top: 52px;
    padding-bottom: 42px;
  }

  .hero h1,
  .page-intro h1,
  .book-intro h1,
  .lesson-intro h1,
  .feature-intro h1,
  .article-shell article > header h1,
  .not-found h1 {
    font-size: clamp(36px, 11vw, 48px);
  }

  .hero-copy > p,
  .page-intro > p,
  .book-intro p,
  .lesson-intro > p:last-of-type,
  .feature-intro p {
    font-size: 17px;
  }

  .reader-preview {
    aspect-ratio: 1.42;
  }

  .columns,
  .study-and-guide,
  .contact-panel {
    grid-template-columns: 1fr;
  }

  .workflow ol,
  .numbered-flow {
    gap: 26px;
    grid-template-columns: 1fr;
  }

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

  .home-actions .button {
    width: 100%;
  }

  .guide-action {
    justify-content: center;
  }

  .course-summary {
    min-height: 96px;
    gap: 14px;
    padding: 12px 46px 12px 12px;
    grid-template-columns: 48px minmax(0, 1fr);
  }

  .course-summary > img {
    width: 48px;
    height: 70px;
  }

  .course-summary > b {
    display: none;
  }

  .course-summary::after {
    right: 20px;
  }

  .course-summary strong {
    font-size: 17px;
  }

  .course-lessons {
    padding-inline: 14px;
  }

  .workflow li {
    padding-right: 0;
  }

  .workflow li::after {
    display: none;
  }

  .book-row,
  .guide-row {
    min-height: 96px;
    gap: 12px;
    padding: 14px 0;
    grid-template-columns: minmax(0, 1fr) 22px;
  }

  .book-row .book-mark,
  .book-row > span:nth-child(2),
  .book-row .book-summary,
  .guide-row > svg:first-child,
  .guide-row > strong,
  .guide-row > span {
    grid-column: 1;
  }

  .book-row > svg,
  .guide-row > svg:last-child {
    grid-row: 1 / span 3;
    grid-column: 2;
  }

  .book-summary {
    display: none;
  }

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

  .site-footer {
    display: flex;
    align-items: flex-start;
    flex-direction: column;
    padding-top: 34px;
    padding-bottom: 34px;
  }

  .site-footer nav {
    flex-wrap: wrap;
    justify-content: flex-start;
    gap: 13px 20px;
  }

  .book-intro {
    align-items: flex-start;
    flex-direction: column;
    gap: 26px;
  }

  .lesson-head {
    display: none;
  }

  .lesson-row {
    display: grid;
    min-height: 100px;
    gap: 4px 12px;
    padding: 16px 0;
    grid-template-columns: 84px minmax(0, 1fr) 22px;
  }

  .lesson-row > span {
    grid-row: 1;
    grid-column: 1;
  }

  .lesson-row strong {
    grid-row: 1;
    grid-column: 2;
  }

  .lesson-row small {
    grid-row: 2;
    grid-column: auto;
    font-size: 12px;
  }

  .lesson-row > svg {
    grid-row: 1 / span 2;
    grid-column: 3;
  }

  .study-and-guide > div {
    padding-right: 0;
    padding-bottom: 30px;
    border-right: 0;
    border-bottom: 1px solid var(--site-line);
  }

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

  .lesson-neighbors {
    grid-template-columns: 1fr;
  }

  .lesson-neighbors > span {
    display: none;
  }

  .lesson-neighbors a + a,
  .lesson-neighbors span + a {
    align-items: flex-start;
    border-top: 1px solid var(--site-line);
    border-left: 0;
    text-align: left;
  }

  .lesson-facts div:nth-child(2) {
    border-right: 0;
  }

  .lesson-facts div:nth-child(-n + 2) {
    border-bottom: 1px solid var(--site-line);
  }

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

  .check-list li {
    border-right: 0;
  }

  .guide-index > a {
    min-height: 142px;
    gap: 8px;
    padding-right: 36px;
    grid-template-columns: 1fr;
  }

  .guide-index > a p {
    font-size: 14px;
  }

  .article-shell article {
    margin-top: 34px;
  }

  .article-meta {
    flex-direction: column;
    gap: 2px;
  }

  .article-meta span::after {
    display: none;
  }

  .lead {
    font-size: 18px;
  }

  .article-next {
    padding: 24px;
  }

  .feature-intro {
    gap: 14px;
    grid-template-columns: 1fr;
  }

  .feature-index > a {
    gap: 16px;
    grid-template-columns: 54px minmax(0, 1fr) 22px;
  }

  .feature-index > a > b {
    font-size: 25px;
  }
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
  }
}