:root {
  color-scheme: light;
  --bg: #f5f0e7;
  --bg-soft: #faf6ee;
  --surface: #fffdf8;
  --surface-raised: #ffffff;
  --text: #2a2620;
  --text-soft: #4c463c;
  --muted: #827a6e;
  --faint: #aaa291;
  --line: #e6ddcd;
  --line-strong: #d8ccb8;
  --accent: #9a4a28;
  --accent-soft: rgba(154, 74, 40, 0.11);
  --accent-contrast: #ffffff;
  --shadow: 0 18px 50px rgba(68, 50, 27, 0.08);
  --topbar-h: 62px;
  --drawer-w: 316px;
  --reader-max: 42rem;
  --serif: "Iowan Old Style", "Palatino Linotype", "Book Antiqua", Palatino, Georgia, "Songti SC", "STSong", "SimSun", "Noto Serif CJK SC", "Source Han Serif SC", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, "PingFang SC", "Hiragino Sans GB", "Microsoft YaHei", sans-serif;
  --reader-size: 1.125rem;
}

html[data-theme="dark"] {
  color-scheme: dark;
  --bg: #11100e;
  --bg-soft: #181612;
  --surface: #1b1915;
  --surface-raised: #232018;
  --text: #ebe3d5;
  --text-soft: #d4cab9;
  --muted: #9b927f;
  --faint: #6c6558;
  --line: #332f28;
  --line-strong: #4a4438;
  --accent: #d07b52;
  --accent-soft: rgba(208, 123, 82, 0.15);
  --accent-contrast: #17130f;
  --shadow: 0 18px 60px rgba(0, 0, 0, 0.35);
}

* {
  box-sizing: border-box;
}

html {
  scroll-behavior: smooth;
  scroll-padding-top: calc(var(--topbar-h) + 18px);
  -webkit-text-size-adjust: 100%;
}

body {
  margin: 0;
  background:
    radial-gradient(circle at 12% 0%, rgba(154, 74, 40, 0.045), transparent 32rem),
    var(--bg);
  color: var(--text);
  font-family: var(--sans);
  line-height: 1.6;
  min-height: 100vh;
  transition: background-color 220ms ease, color 220ms ease;
}

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

button {
  font: inherit;
}

h1,
h2,
h3,
h4,
p {
  margin-top: 0;
}

svg {
  width: 22px;
  height: 22px;
  fill: none;
  stroke: currentColor;
  stroke-width: 1.8;
  stroke-linecap: round;
  stroke-linejoin: round;
}

/* Top bar */
.topbar {
  position: sticky;
  top: 0;
  z-index: 300;
  height: var(--topbar-h);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  padding: 0 max(14px, env(safe-area-inset-left)) 0 max(14px, env(safe-area-inset-right));
  background: color-mix(in srgb, var(--bg) 88%, transparent);
  border-bottom: 1px solid var(--line);
  backdrop-filter: blur(18px) saturate(1.15);
  -webkit-backdrop-filter: blur(18px) saturate(1.15);
}

.topbar__start,
.topbar__end,
.reader-controls {
  display: flex;
  align-items: center;
  gap: 8px;
}

.brand {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  font-weight: 600;
  letter-spacing: -0.01em;
}

.brand__mark {
  display: grid;
  place-items: center;
  width: 34px;
  height: 34px;
  flex: 0 0 34px;
  border-radius: 11px;
  background: var(--text);
  color: var(--bg);
  font-family: var(--serif);
  font-size: 0.78rem;
  letter-spacing: 0.04em;
}

.brand__text {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 0.95rem;
}

.icon-button {
  width: 38px;
  height: 38px;
  padding: 0;
  display: inline-grid;
  place-items: center;
  border: 1px solid transparent;
  border-radius: 12px;
  background: transparent;
  color: var(--text-soft);
  cursor: pointer;
  transition: background-color 160ms ease, border-color 160ms ease, color 160ms ease, transform 160ms ease;
}

.icon-button:hover {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: color-mix(in srgb, var(--accent) 18%, transparent);
}

.icon-button:active {
  transform: scale(0.94);
}

.theme-toggle .icon-moon {
  display: none;
}

html[data-theme="dark"] .theme-toggle .icon-sun {
  display: none;
}

html[data-theme="dark"] .theme-toggle .icon-moon {
  display: block;
}

.reader-controls {
  margin-right: 2px;
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: color-mix(in srgb, var(--surface) 75%, transparent);
}

.reader-controls .icon-button {
  width: 31px;
  height: 31px;
  border-radius: 999px;
  font-size: 0.95rem;
  font-weight: 700;
}

.reader-controls__label {
  min-width: 40px;
  text-align: center;
  font-size: 0.75rem;
  font-variant-numeric: tabular-nums;
  color: var(--muted);
}

/* Progress */
.reading-progress {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  z-index: 400;
  height: 3px;
  background: transparent;
  pointer-events: none;
}

.reading-progress span {
  display: block;
  width: 0;
  height: 100%;
  background: var(--accent);
  transition: width 80ms linear;
}

/* Reader layout + drawer */
.reader-layout {
  padding: 0 20px 80px;
}

.reader {
  max-width: var(--reader-max);
  margin: 0 auto;
  padding: 36px 0 20px;
  font-family: var(--serif);
  font-size: var(--reader-size);
  line-height: 1.9;
}

.chapter-drawer {
  position: fixed;
  top: var(--topbar-h);
  bottom: 0;
  left: 0;
  z-index: 260;
  width: min(var(--drawer-w), 88vw);
  overflow-y: auto;
  padding: 18px 14px 40px;
  background: var(--bg-soft);
  border-right: 1px solid var(--line);
  transform: translateX(-105%);
  transition: transform 240ms cubic-bezier(0.22, 0.9, 0.32, 1);
  overscroll-behavior: contain;
}

.drawer-backdrop {
  position: fixed;
  inset: 0;
  z-index: 250;
  background: rgba(18, 15, 10, 0.42);
  opacity: 0;
  pointer-events: none;
  transition: opacity 220ms ease;
}

body.drawer-open {
  overflow: hidden;
}

body.drawer-open .chapter-drawer {
  transform: translateX(0);
}

body.drawer-open .drawer-backdrop {
  opacity: 1;
  pointer-events: auto;
}

.drawer__header {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 12px;
  padding: 4px 6px 16px;
  border-bottom: 1px solid var(--line);
}

.drawer__eyebrow {
  margin: 0 0 3px;
  color: var(--muted);
  font-size: 0.69rem;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.drawer__header h2 {
  margin: 0;
  font-family: var(--serif);
  font-size: 1.45rem;
  letter-spacing: -0.02em;
}

.drawer__count {
  color: var(--muted);
  font-size: 0.78rem;
  white-space: nowrap;
}

.toc-nav {
  padding-top: 8px;
}

.toc-part {
  padding: 18px 0 4px;
  border-bottom: 1px solid var(--line);
}

.toc-part__header {
  padding: 0 6px 8px;
}

.toc-part__number {
  color: var(--accent);
  font-size: 0.68rem;
  font-weight: 700;
  letter-spacing: 0.14em;
  text-transform: uppercase;
}

.toc-part__header h3 {
  margin: 4px 0 0;
  font-family: var(--serif);
  font-size: 1.08rem;
  letter-spacing: -0.01em;
}

.toc-part__header p {
  margin: 2px 0 0;
  color: var(--muted);
  font-size: 0.72rem;
  letter-spacing: 0.04em;
}

.toc-part__chapters {
  list-style: none;
  margin: 0;
  padding: 0;
}

.toc-part__chapters a {
  display: flex;
  align-items: baseline;
  gap: 10px;
  padding: 8px 6px;
  border-radius: 10px;
  color: var(--text-soft);
  transition: background-color 150ms ease, color 150ms ease;
}

.toc-part__chapters a:hover {
  background: var(--accent-soft);
  color: var(--text);
}

.toc-part__chapters a.is-current {
  background: var(--accent);
  color: var(--accent-contrast);
}

.chapter-link__number {
  flex: 0 0 24px;
  color: var(--faint);
  font-family: var(--sans);
  font-size: 0.68rem;
  font-weight: 700;
  font-variant-numeric: tabular-nums;
}

.toc-part__chapters a.is-current .chapter-link__number,
.toc-part__chapters a:hover .chapter-link__number {
  color: inherit;
  opacity: 0.78;
}

.chapter-link__title {
  min-width: 0;
  font-size: 0.88rem;
}

/* Chapter navigation */
.chapter-nav {
  display: grid;
  grid-template-columns: 1fr auto 1fr;
  align-items: center;
  gap: 12px;
  font-family: var(--sans);
}

.chapter-nav--top {
  margin-bottom: 30px;
}

.chapter-nav--bottom {
  margin-top: 52px;
  padding-top: 22px;
  border-top: 1px solid var(--line);
}

.chapter-nav__link {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  padding: 10px 12px;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: color-mix(in srgb, var(--surface) 76%, transparent);
  transition: background-color 160ms ease, border-color 160ms ease, transform 160ms ease;
}

.chapter-nav__link:hover {
  background: var(--surface-raised);
  border-color: var(--line-strong);
  transform: translateY(-1px);
}

.chapter-nav__link--next {
  justify-content: flex-end;
  text-align: right;
}

.chapter-nav__direction {
  color: var(--accent);
  font-size: 1.15rem;
}

.chapter-nav__text {
  display: flex;
  flex-direction: column;
  min-width: 0;
}

.chapter-nav__text small {
  color: var(--muted);
  font-size: 0.68rem;
  letter-spacing: 0.05em;
}

.chapter-nav__text strong {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-weight: 650;
  font-size: 0.84rem;
}

.chapter-nav__center {
  color: var(--muted);
  font-size: 0.76rem;
  font-variant-numeric: tabular-nums;
  white-space: nowrap;
}

.chapter-nav__home {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  min-width: 42px;
  height: 32px;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: 999px;
  color: var(--text-soft);
  font-size: 0.78rem;
}

.chapter-nav__home:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.chapter-nav__spacer {
  min-width: 80px;
}

.chapter-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin: 0 0 30px;
  padding-bottom: 14px;
  border-bottom: 1px solid var(--line);
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.72rem;
  letter-spacing: 0.06em;
}

.chapter-meta__part {
  color: var(--accent);
  font-weight: 700;
}

/* Markdown body */
.markdown-body {
  color: var(--text-soft);
  font-family: var(--serif);
  font-size: var(--reader-size);
  line-height: 1.92;
  overflow-wrap: break-word;
}

.markdown-body > :first-child {
  margin-top: 0;
}

.markdown-body h1,
.markdown-body h2,
.markdown-body h3,
.markdown-body h4 {
  color: var(--text);
  font-weight: 600;
  line-height: 1.32;
  letter-spacing: -0.018em;
}

.markdown-body h1 {
  margin: 0 0 16px;
  font-size: 2.05em;
  line-height: 1.16;
  letter-spacing: -0.035em;
}

.markdown-body h2 {
  margin: 2.35em 0 0.75em;
  font-size: 1.42em;
}

.markdown-body h3 {
  margin: 2em 0 0.6em;
  font-size: 1.14em;
}

.markdown-body p {
  margin: 0 0 1.15em;
}

.markdown-body > h1:first-child + blockquote {
  margin: 0 0 1.4em;
  padding: 0 0 0 18px;
  border-left: 2px solid var(--accent);
  color: var(--muted);
  font-size: 0.88em;
  line-height: 1.7;
}

.markdown-body blockquote {
  margin: 1.5em 0;
  padding: 0.65em 1.1em;
  border-left: 3px solid var(--accent);
  border-radius: 0 12px 12px 0;
  background: var(--accent-soft);
  color: var(--text-soft);
}

.markdown-body blockquote p {
  margin: 0.25em 0;
}

.markdown-body ul,
.markdown-body ol {
  margin: 1.05em 0 1.3em;
  padding-left: 1.35em;
}

.markdown-body li {
  margin: 0.35em 0;
  padding-left: 0.18em;
}

.markdown-body li::marker {
  color: var(--accent);
  font-weight: 700;
}

.markdown-body strong {
  color: var(--text);
  font-weight: 700;
}

.markdown-body em {
  letter-spacing: 0.005em;
}

.markdown-body hr {
  width: 46px;
  margin: 2.4rem auto;
  border: 0;
  border-top: 2px solid var(--line-strong);
  border-radius: 2px;
  opacity: 0.7;
}

.markdown-body a {
  color: var(--accent);
  text-decoration: underline;
  text-decoration-thickness: 0.06em;
  text-underline-offset: 0.18em;
  text-decoration-color: color-mix(in srgb, var(--accent) 38%, transparent);
}

.markdown-body a:hover {
  text-decoration-color: currentColor;
}

.markdown-body > p:last-child {
  margin-top: 2rem;
  padding-top: 1.2rem;
  border-top: 1px solid var(--line);
  color: var(--muted);
  font-family: var(--sans);
  font-size: 0.76em;
  text-align: center;
}

.markdown-body > p:last-child a {
  margin: 0 2px;
}

/* Home */
.home-layout {
  width: min(1120px, 100%);
  margin: 0 auto;
  padding: 56px 20px 72px;
}

.home-hero {
  max-width: 720px;
  margin: 0 auto 58px;
  text-align: center;
}

.home-hero__kicker {
  margin: 0 0 18px;
  color: var(--accent);
  font-size: 0.74rem;
  font-weight: 700;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.home-hero h1 {
  margin: 0;
  color: var(--text);
  font-family: var(--serif);
  font-size: clamp(2.45rem, 8vw, 5rem);
  line-height: 1.02;
  letter-spacing: -0.052em;
}

.home-hero__subtitle {
  margin: 14px 0 0;
  color: var(--text-soft);
  font-family: var(--serif);
  font-size: clamp(1.15rem, 3vw, 1.55rem);
  letter-spacing: 0.08em;
}

.home-hero__meta {
  margin: 14px 0 26px;
  color: var(--muted);
  font-size: 0.85rem;
}

.continue-link {
  display: inline-flex;
  align-items: center;
  gap: 10px;
  max-width: 100%;
  padding: 11px 15px;
  border: 1px solid var(--line-strong);
  border-radius: 999px;
  background: var(--surface);
  box-shadow: var(--shadow);
  color: var(--text);
  transition: transform 160ms ease, border-color 160ms ease;
}

.continue-link:hover {
  transform: translateY(-2px);
  border-color: var(--accent);
}

.continue-link__label {
  color: var(--accent);
  font-size: 0.75rem;
  font-weight: 700;
  letter-spacing: 0.06em;
  white-space: nowrap;
}

.continue-link__chapter {
  max-width: 280px;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  color: var(--text-soft);
  font-size: 0.85rem;
}

.continue-link__arrow {
  color: var(--muted);
}

.book-toc {
  display: grid;
  gap: 24px;
}

.part-card {
  padding: 26px;
  border: 1px solid var(--line);
  border-radius: 24px;
  background: var(--surface);
  box-shadow: var(--shadow);
}

.part-card__header {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) minmax(180px, 320px);
  align-items: start;
  gap: 16px 22px;
  padding-bottom: 20px;
  border-bottom: 1px solid var(--line);
}

.part-card__index {
  display: grid;
  place-items: center;
  min-width: 54px;
  height: 54px;
  padding: 0 10px;
  border-radius: 16px;
  background: var(--accent-soft);
  color: var(--accent);
  font-size: 0.76rem;
  font-weight: 800;
  letter-spacing: 0.08em;
  text-transform: uppercase;
}

.part-card__title-group h2 {
  margin: 2px 0 0;
  font-family: var(--serif);
  font-size: 1.55rem;
  letter-spacing: -0.035em;
}

.part-card__title-group p {
  margin: 5px 0 0;
  color: var(--muted);
  font-size: 0.78rem;
  letter-spacing: 0.06em;
  text-transform: uppercase;
}

.part-card__description {
  margin: 2px 0 0;
  color: var(--text-soft);
  font-family: var(--serif);
  font-size: 0.96rem;
  line-height: 1.7;
}

.chapter-grid {
  list-style: none;
  margin: 18px 0 0;
  padding: 0;
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 4px 12px;
}

.chapter-grid a {
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 11px 10px;
  border-radius: 12px;
  color: var(--text-soft);
  transition: background-color 150ms ease, color 150ms ease, transform 150ms ease;
}

.chapter-grid a:hover {
  background: var(--accent-soft);
  color: var(--text);
  transform: translateX(2px);
}

.chapter-grid__number {
  flex: 0 0 26px;
  color: var(--faint);
  font-size: 0.68rem;
  font-weight: 800;
  font-variant-numeric: tabular-nums;
}

.chapter-grid a:hover .chapter-grid__number {
  color: var(--accent);
}

.chapter-grid__title {
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 0.9rem;
}

.chapter-grid__arrow {
  margin-left: auto;
  color: var(--faint);
  opacity: 0;
  transform: translateX(-4px);
  transition: opacity 150ms ease, transform 150ms ease;
}

.chapter-grid a:hover .chapter-grid__arrow {
  opacity: 1;
  transform: translateX(0);
}

.home-footer {
  margin-top: 42px;
  color: var(--muted);
  text-align: center;
  font-size: 0.78rem;
  line-height: 1.7;
}

/* Error page */
.error-page {
  width: min(560px, 100%);
  margin: 90px auto;
  text-align: center;
}

.error-page__code {
  margin: 0;
  color: var(--accent);
  font-family: var(--serif);
  font-size: 5rem;
  font-weight: 700;
  line-height: 1;
}

.error-page h1 {
  margin: 12px 0;
  font-family: var(--serif);
  font-size: 2rem;
}

.error-page p {
  color: var(--muted);
}

.button {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: 12px 18px;
  border-radius: 999px;
  background: var(--accent);
  color: var(--accent-contrast);
  font-weight: 700;
}

/* Desktop sidebar */
@media (min-width: 980px) {
  .reading-page .reader-layout {
    margin-left: var(--drawer-w);
    padding-right: max(36px, env(safe-area-inset-right));
    padding-left: max(36px, env(safe-area-inset-left));
  }

  .chapter-drawer {
    transform: none;
  }

  .drawer-backdrop {
    display: none;
  }

  .reading-page.sidebar-closed .chapter-drawer {
    transform: translateX(-105%);
  }

  .reading-page.sidebar-closed .reader-layout {
    margin-left: 0;
  }
}

/* Mobile + tablet */
@media (max-width: 760px) {
  :root {
    --topbar-h: 58px;
  }

  .brand__text {
    font-size: 0.88rem;
  }

  .reader-layout {
    padding: 0 16px 56px;
  }

  .reader {
    padding-top: 24px;
    line-height: 1.88;
  }

  .chapter-nav {
    gap: 8px;
  }

  .chapter-nav__link {
    padding: 9px 8px;
    gap: 6px;
    border-radius: 12px;
  }

  .chapter-nav__direction {
    font-size: 0.95rem;
  }

  .chapter-nav__text strong {
    font-size: 0.73rem;
  }

  .chapter-nav__text small {
    font-size: 0.62rem;
  }

  .chapter-nav__spacer {
    min-width: 20px;
  }

  .chapter-nav__center {
    font-size: 0.68rem;
  }

  .markdown-body h1 {
    font-size: 1.78em;
  }

  .part-card {
    padding: 20px 16px;
    border-radius: 20px;
  }

  .part-card__header {
    grid-template-columns: auto minmax(0, 1fr);
  }

  .part-card__description {
    grid-column: 1 / -1;
    margin-top: 0;
  }

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

  .home-layout {
    padding-top: 42px;
  }
}

@media (max-width: 420px) {
  .reader-controls__label {
    min-width: 32px;
  }

  .brand__text {
    max-width: 135px;
  }

  .home-hero h1 {
    letter-spacing: -0.04em;
  }
}

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