:root {
  --learn: #2f776c;
  --book-paper: #fff;
  --book-surface: #fff;
  --book-ink: #202622;
  --book-muted: #66706a;
  --book-line: #d9ded9;
  --book-accent: var(--learn);
  --book-accent-soft: #edf4f2;
  --book-serif: "Noto Serif TC", "Songti TC", "PMingLiU", serif;
  --book-sans: Arial, "Noto Sans TC", sans-serif;
}

html {
  scroll-behavior: smooth;
}

body.learning-book-page {
  min-width: 320px;
  margin: 0;
  overflow-x: clip;
  color: var(--book-ink);
  background: var(--book-paper);
  font-family: var(--book-sans);
}

.learning-book-page a {
  color: inherit;
}

.learning-book-page :focus-visible {
  outline: 2px solid var(--book-accent);
  outline-offset: 4px;
}

.learning-skip-link {
  position: fixed;
  inset-block-start: 8px;
  inset-inline-start: 8px;
  z-index: 1000;
  translate: 0 -160%;
  padding: 10px 14px;
  color: #fff;
  background: var(--book-accent);
  font-size: 14px;
  font-weight: 700;
  text-decoration: none;
}

.learning-skip-link:focus {
  translate: 0;
}

.learning-site-bar {
  color: var(--book-ink);
  background: rgb(255 255 255 / 96%);
  border-block-end: 1px solid var(--book-line);
}

.learning-site-bar__inner {
  display: grid;
  grid-template-columns: minmax(250px, 1fr) auto;
  gap: 12px 32px;
  width: min(1120px, calc(100% - 40px));
  margin-inline: auto;
  padding-block: 18px 14px;
}

.learning-site-brand {
  display: inline-flex;
  width: fit-content;
  align-items: center;
  gap: 12px;
  text-decoration: none;
}

.learning-site-brand__mark {
  box-sizing: border-box;
  display: grid;
  width: 36px;
  height: 36px;
  flex: 0 0 36px;
  place-items: center;
  color: var(--book-accent);
  background: transparent;
  border: 1.5px solid var(--book-accent);
  font-family: var(--book-serif);
  font-size: 21px;
  font-weight: 500;
  transition: transform .18s ease, background-color .18s ease, color .18s ease;
}

.learning-site-brand:hover .learning-site-brand__mark,
.learning-site-brand:focus-visible .learning-site-brand__mark {
  transform: translate(-2px, -2px);
  color: #fff;
  background: var(--book-accent);
}

.learning-site-brand strong,
.learning-site-brand small {
  display: block;
}

.learning-site-brand strong {
  font-family: var(--book-serif);
  font-size: 18px;
  letter-spacing: .02em;
}

.learning-site-brand small {
  margin-block-start: 2px;
  color: var(--book-muted);
  font-size: 11px;
  letter-spacing: .04em;
}

.learning-site-nav {
  display: flex;
  align-items: center;
  gap: 6px;
}

.learning-site-nav a {
  min-height: 44px;
  padding: 11px 12px;
  color: var(--book-muted);
  font-size: 13px;
  font-weight: 700;
  text-decoration: none;
}

.learning-site-nav a:hover,
.learning-site-nav a:focus-visible,
.learning-site-nav a[aria-current="page"] {
  color: var(--book-ink);
  background: var(--book-accent-soft);
}

.learning-site-context {
  grid-column: 1 / -1;
  display: flex;
  align-items: center;
  gap: 10px;
  margin: 0;
  padding-block-start: 10px;
  color: var(--book-muted);
  border-block-start: 1px solid var(--book-line);
  font-size: 12px;
}

.learning-site-context span {
  color: var(--book-ink);
  font-weight: 800;
}

.learning-site-context .book-category {
  color: var(--book-accent);
}

.book-category--psychology {
  color: #2f776c;
}

.book-category--worldview {
  color: #8a5f00;
}

.learning-site-context time::before {
  margin-inline-end: 10px;
  color: #aeb7b1;
  content: "•";
}

.book-hub {
  width: min(960px, calc(100% - 40px));
  margin-inline: auto;
  padding-block: 28px 100px;
}

.reading-article {
  width: min(740px, calc(100% - 40px));
  margin-inline: auto;
  padding-block: 28px 96px;
}

.book-hero,
.reading-header {
  padding-block: clamp(60px, 9vw, 112px) clamp(48px, 7vw, 80px);
  border-block-end: 1px solid var(--book-line);
}

.book-kicker,
.book-section-heading > p {
  margin: 0 0 16px;
  color: var(--book-accent);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: .14em;
  text-transform: uppercase;
}

.book-hero h1,
.reading-header h1 {
  max-width: 820px;
  margin: 0;
  font-family: var(--book-serif);
  font-size: clamp(40px, 7vw, 76px);
  font-weight: 500;
  line-height: 1.22;
  letter-spacing: -.045em;
}

.reading-header h1 {
  font-size: clamp(37px, 6vw, 58px);
}

.book-introduction {
  max-width: 700px;
  margin-block-start: 34px;
  color: #3e4943;
  font-size: 17px;
  line-height: 1.9;
}

.book-introduction p {
  margin: 0 0 18px;
}

.book-introduction blockquote {
  margin: 22px 0 0;
  padding: 18px 0 18px 22px;
  color: var(--book-muted);
  border-inline-start: 2px solid var(--book-accent);
}

.book-introduction blockquote p {
  margin: 0;
}

.book-attribution,
.reading-meta {
  margin: 28px 0 0;
  color: var(--book-muted);
  font-size: 12px;
  line-height: 1.9;
}

.book-index {
  padding-block-start: 72px;
}

.book-section-heading {
  display: grid;
  grid-template-columns: 150px 1fr;
  align-items: end;
  gap: 20px;
  margin-block-end: 24px;
}

.book-section-heading > p {
  margin: 0 0 5px;
}

.book-section-heading h2 {
  margin: 0;
  font-family: var(--book-serif);
  font-size: clamp(28px, 4vw, 40px);
  font-weight: 500;
}

.book-index ol,
.book-index ul {
  margin: 0;
  padding: 0;
  border-block-start: 1px solid var(--book-line);
  list-style: none;
}

.book-index li {
  border-block-end: 1px solid var(--book-line);
}

.book-index li a {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr) auto;
  gap: 22px;
  align-items: center;
  min-height: 76px;
  padding: 14px 8px;
  text-decoration: none;
  transition: padding-inline .18s ease, color .18s ease, background-color .18s ease;
}

.book-index li a:hover,
.book-index li a:focus-visible {
  padding-inline: 14px;
  color: var(--book-accent);
  background: rgb(47 119 108 / 4%);
}

.book-index li span,
.book-index li small {
  color: var(--book-muted);
  font-size: 11px;
  letter-spacing: .08em;
}

.book-index li strong {
  font-family: var(--book-serif);
  font-size: 19px;
  font-weight: 500;
}

.book-index li small {
  text-align: end;
}

.reading-header {
  padding-block-start: clamp(56px, 8vw, 92px);
}

.chapter-body {
  padding-block: clamp(52px, 8vw, 78px);
  color: #29312d;
  font-family: var(--book-serif);
  font-size: 18.5px;
  line-height: 2.02;
  overflow-wrap: anywhere;
}

.chapter-body > :first-child {
  margin-block-start: 0;
}

.chapter-body > :last-child {
  margin-block-end: 0;
}

.chapter-body p {
  margin: 0 0 1.55em;
}

.chapter-body h2,
.chapter-body h3,
.chapter-body h4 {
  color: var(--book-ink);
  font-family: var(--book-sans);
  font-weight: 750;
  line-height: 1.45;
  letter-spacing: -.02em;
}

.chapter-body h2 {
  margin: 2.55em 0 .9em;
  padding-block-start: .25em;
  font-size: 25px;
}

.chapter-body h3 {
  margin: 2.2em 0 .8em;
  font-size: 21px;
}

.chapter-body h4 {
  margin: 2em 0 .75em;
  font-size: 19px;
}

.chapter-body strong {
  color: #1d4f47;
  font-weight: 750;
}

.chapter-body blockquote {
  margin: 2em 0;
  padding: .35em 0 .35em 1.25em;
  color: #4e5c55;
  border-inline-start: 2px solid var(--book-accent);
}

.chapter-body blockquote p {
  margin: 0;
}

.chapter-body ul,
.chapter-body ol {
  margin: 0 0 1.75em;
  padding-inline-start: 1.35em;
}

.chapter-body li {
  margin-block: .35em;
  padding-inline-start: .25em;
}

.chapter-body code {
  padding: .12em .35em;
  color: #244e48;
  background: var(--book-accent-soft);
  border-radius: 2px;
  font-family: Consolas, "SFMono-Regular", monospace;
  font-size: .86em;
}

.chapter-body a {
  color: var(--book-accent);
  text-decoration-line: underline;
  text-decoration-thickness: 1px;
  text-underline-offset: 4px;
  text-decoration-skip-ink: auto;
}

.reading-note {
  margin: 0 0 34px;
  padding: 18px 0;
  color: var(--book-muted);
  border-block: 1px solid var(--book-line);
  font-size: 13px;
  line-height: 1.8;
}

.chapter-nav,
.supplement-nav {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  margin-block-start: 12px;
  border-block: 1px solid var(--book-line);
}

.chapter-nav a,
.supplement-nav a {
  display: flex;
  min-height: 92px;
  flex-direction: column;
  justify-content: center;
  padding: 18px;
  border-inline-end: 1px solid var(--book-line);
  font-family: var(--book-serif);
  font-size: 14px;
  line-height: 1.55;
  text-decoration: none;
}

.chapter-nav a:last-child,
.supplement-nav a:last-child {
  border-inline-end: 0;
}

.chapter-nav a:hover,
.chapter-nav a:focus-visible,
.supplement-nav a:hover,
.supplement-nav a:focus-visible {
  color: var(--book-accent);
  background: var(--book-accent-soft);
}

.chapter-nav span {
  margin-block-end: 5px;
  color: var(--book-muted);
  font-family: var(--book-sans);
  font-size: 10px;
  font-weight: 800;
  letter-spacing: .1em;
}

.supplement-nav {
  grid-template-columns: 1fr;
}

.supplement-nav a {
  align-items: center;
}

.book-footer {
  color: #e8ece9;
  background: #26302b;
}

.book-footer__inner {
  display: grid;
  grid-template-columns: minmax(220px, 1fr) auto;
  gap: 28px 40px;
  width: min(1120px, calc(100% - 40px));
  margin-inline: auto;
  padding-block: 46px 24px;
}

.book-footer p {
  margin: 0;
  color: #b8c3bd;
  font-size: 12px;
  line-height: 1.8;
}

.book-footer p strong {
  color: #fff;
  font-family: var(--book-serif);
  font-size: 16px;
  font-weight: 500;
}

.book-footer__links {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 20px;
  align-items: start;
  font-size: 12px;
}

.book-footer__links a {
  color: #cad2cd;
  text-decoration: none;
}

.book-footer__links a:hover,
.book-footer__links a:focus-visible {
  color: #fff;
  text-decoration: underline;
  text-underline-offset: 4px;
}

.book-footer small {
  grid-column: 1 / -1;
  padding-block-start: 18px;
  color: #8f9c95;
  border-block-start: 1px solid #48534d;
  font-size: 10px;
}

@media (max-width: 720px) {
  .learning-site-bar__inner {
    grid-template-columns: 1fr;
    width: min(100% - 28px, 1120px);
  }

  .learning-site-nav {
    justify-content: space-between;
    gap: 2px;
    border-block-start: 1px solid var(--book-line);
  }

  .learning-site-nav a {
    flex: 1 1 auto;
    padding-inline: 7px;
    text-align: center;
  }

  .learning-site-context {
    padding-block-start: 8px;
  }

  .book-hub,
  .reading-article {
    width: min(960px, calc(100% - 40px));
    padding-block-start: 20px;
  }

  .book-hero,
  .reading-header {
    padding-block: 52px 44px;
  }

  .book-hero h1,
  .reading-header h1 {
    letter-spacing: -.035em;
  }

  .book-introduction {
    font-size: 16px;
  }

  .book-section-heading {
    grid-template-columns: 1fr;
    gap: 4px;
  }

  .book-index {
    padding-block-start: 58px;
  }

  .book-index li a {
    grid-template-columns: 58px minmax(0, 1fr);
    gap: 12px;
    min-height: 72px;
  }

  .book-index li small {
    display: none;
  }

  .chapter-body {
    padding-block: 50px;
    font-size: 19px;
    line-height: 2;
  }

  .chapter-body h2 {
    font-size: 23px;
  }

  .chapter-nav {
    grid-template-columns: 1fr;
  }

  .chapter-nav a {
    min-height: 74px;
    border-inline-end: 0;
    border-block-end: 1px solid var(--book-line);
  }

  .chapter-nav a:last-child {
    border-block-end: 0;
  }

  .book-footer__inner {
    grid-template-columns: 1fr;
    width: min(100% - 30px, 1120px);
  }

  .book-footer small {
    grid-column: auto;
  }
}

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

  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: .01ms !important;
  }
}

@media print {
  .learning-site-bar,
  .book-footer,
  .chapter-nav,
  .supplement-nav {
    display: none;
  }

  body.learning-book-page {
    color: #000;
    background: #fff;
  }

  .reading-article,
  .book-hub {
    width: 100%;
    padding: 0;
  }
}