:root {
  --text-xs: clamp(0.75rem, 0.72rem + 0.18vw, 0.875rem);
  --text-sm: clamp(0.9rem, 0.84rem + 0.22vw, 1rem);
  --text-base: clamp(1rem, 0.95rem + 0.28vw, 1.12rem);
  --text-lg: clamp(1.18rem, 1.04rem + 0.65vw, 1.5rem);
  --text-xl: clamp(1.55rem, 1.25rem + 1.1vw, 2.2rem);
  --text-2xl: clamp(2.25rem, 1.55rem + 2.8vw, 4.5rem);
  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-5: 1.25rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --radius-sm: 0.45rem;
  --radius-md: 0.85rem;
  --radius-lg: 1.25rem;
  --font-display: "Noto Serif SC", "Songti SC", "STSong", serif;
  --font-body: "Noto Serif SC", "Songti SC", "STSong", serif;
  --font-sans: "Noto Sans SC", "PingFang SC", "Microsoft YaHei", sans-serif;
  --content-wide: 1180px;
  --content-read: 860px;
  --transition: 220ms cubic-bezier(0.16, 1, 0.3, 1);
}

:root,
[data-theme="light"] {
  --color-bg: #f5efe5;
  --color-bg-2: #fbf7f1;
  --color-surface: rgba(251, 247, 241, 0.84);
  --color-surface-strong: #f9f3ea;
  --color-surface-soft: #f1e6d8;
  --color-border: #d8c9b2;
  --color-divider: rgba(102, 73, 41, 0.12);
  --color-text: #2f2518;
  --color-text-muted: #756653;
  --color-text-soft: #a4937d;
  --color-primary: #8d5222;
  --color-primary-strong: #6f3f16;
  --color-chip: rgba(141, 82, 34, 0.08);
  --color-shadow: rgba(62, 42, 24, 0.1);
  --color-ink: rgba(47, 37, 24, 0.05);
}

[data-theme="dark"] {
  --color-bg: #161412;
  --color-bg-2: #1b1916;
  --color-surface: rgba(30, 27, 23, 0.9);
  --color-surface-strong: #22201b;
  --color-surface-soft: #2c2821;
  --color-border: #41392e;
  --color-divider: rgba(214, 194, 166, 0.12);
  --color-text: #ddd2c1;
  --color-text-muted: #a69883;
  --color-text-soft: #706656;
  --color-primary: #d0a16d;
  --color-primary-strong: #e6bb85;
  --color-chip: rgba(208, 161, 109, 0.12);
  --color-shadow: rgba(0, 0, 0, 0.34);
  --color-ink: rgba(221, 210, 193, 0.04);
}

*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  scroll-padding-top: 5rem;
}

body {
  margin: 0;
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.9;
  color: var(--color-text);
  background: var(--color-bg);
  overflow-x: hidden;
}

body.nav-open,
body.tooltip-open {
  overflow: hidden;
}

button,
a {
  color: inherit;
  font: inherit;
}

button {
  border: 0;
  background: none;
  cursor: pointer;
}

a {
  color: var(--color-primary);
  text-decoration: none;
}

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

::selection {
  background: rgba(141, 82, 34, 0.18);
}

:focus-visible {
  outline: 2px solid var(--color-primary);
  outline-offset: 3px;
  border-radius: var(--radius-sm);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    animation: none !important;
    transition-duration: 0.01ms !important;
    scroll-behavior: auto !important;
  }
}

.ink-bg {
  position: fixed;
  inset: 0;
  pointer-events: none;
  background: radial-gradient(ellipse 36% 24% at 22% 8%, var(--color-ink), transparent);
  opacity: 0.45;
  z-index: 0;
}

.site-header,
.home,
.reader,
.site-footer {
  position: relative;
  z-index: 1;
}

.site-header {
  position: sticky;
  top: 0;
  z-index: 50;
  border-bottom: 1px solid var(--color-divider);
  background: color-mix(in srgb, var(--color-bg) 96%, transparent);
}

.header-inner {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-3) var(--space-6);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.logo {
  display: inline-flex;
  align-items: center;
  gap: var(--space-3);
  color: var(--color-text);
}

.logo-copy {
  display: flex;
  flex-direction: column;
  gap: 0.1rem;
}

.logo-text {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  letter-spacing: 0.18em;
  font-weight: 600;
}

.logo-subtext {
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  letter-spacing: 0.12em;
}

.nav {
  position: relative;
}

.nav-toggle,
.theme-toggle {
  width: 40px;
  height: 40px;
  border-radius: 999px;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  color: var(--color-text-muted);
  background: transparent;
  border: 1px solid var(--color-divider);
  transition: transform var(--transition), color var(--transition), border-color var(--transition);
}

.nav-toggle:hover,
.theme-toggle:hover {
  color: var(--color-text);
  transform: translateY(-1px);
  border-color: var(--color-border);
}

.nav-toggle {
  flex-direction: column;
  gap: 4px;
}

.nav-toggle span {
  width: 18px;
  height: 1.6px;
  border-radius: 999px;
  background: currentColor;
}

.nav-panel {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  width: min(420px, calc(100vw - 2rem));
  max-height: min(78vh, 720px);
  overflow: auto;
  padding: var(--space-5);
  border: 1px solid var(--color-divider);
  border-radius: var(--radius-md);
  background: color-mix(in srgb, var(--color-bg) 98%, transparent);
  opacity: 0;
  pointer-events: none;
  transform: translateY(-8px);
  transition: opacity var(--transition), transform var(--transition);
  overscroll-behavior: contain;
}

.nav-panel.open {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.nav-panel-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
  margin-bottom: var(--space-4);
}

.nav-panel-title {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  letter-spacing: 0.08em;
}

.nav-close {
  display: none;
  width: 34px;
  height: 34px;
  border-radius: 999px;
  background: var(--color-surface-soft);
  color: var(--color-text-muted);
}

.nav-section + .nav-section {
  margin-top: var(--space-5);
  padding-top: var(--space-5);
  border-top: 1px solid var(--color-divider);
}

.nav-section-title {
  margin: 0 0 var(--space-3);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  letter-spacing: 0.08em;
}

.nav-section-list {
  display: grid;
  gap: var(--space-2);
}

.nav-link {
  width: 100%;
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: var(--space-3);
  padding: var(--space-3) var(--space-4);
  border-radius: var(--radius-md);
  text-align: left;
  color: var(--color-text);
  background: transparent;
  border: 1px solid transparent;
  transition: background var(--transition), border-color var(--transition), transform var(--transition);
  min-height: 44px;
}

.nav-link small {
  color: var(--color-text-muted);
  font-family: var(--font-sans);
  font-size: var(--text-xs);
}

.nav-link:hover,
.nav-link.active {
  background: var(--color-chip);
  border-color: var(--color-divider);
  transform: translateY(-1px);
}

.home {
  min-height: calc(100dvh - 73px);
}

.home-content {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-12) var(--space-6) var(--space-12);
}

.home-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  letter-spacing: 0.18em;
  font-weight: 300;
}

.section-badge,
.chapter-label,
.toggle-chip,
.card-label {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-text-muted);
  background: transparent;
  border: 1px solid var(--color-divider);
  border-radius: 999px;
  padding: 0.32rem 0.65rem;
}

.footer-nav-btn,
.back-btn,
.chapter-nav-arrows button,
.toggle-chip {
  transition: background var(--transition), color var(--transition), border-color var(--transition), transform var(--transition);
}
.footer-nav-btn:hover,
.back-btn:hover,
.chapter-nav-arrows button:hover,
.toggle-chip:hover {
  background: var(--color-surface-soft);
  transform: translateY(-1px);
}

.chapter-sections {
  margin-top: var(--space-10);
  display: grid;
  gap: var(--space-8);
}

.chapter-group {
  padding-top: var(--space-3);
}

.chapter-group-head {
  margin-bottom: var(--space-4);
}

.chapter-group-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: var(--text-lg);
  font-weight: 400;
}

.chapter-grid {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  gap: var(--space-3);
}

.chapter-card {
  padding: var(--space-4);
  border-radius: var(--radius-md);
  border: 1px solid var(--color-divider);
  background: transparent;
  text-align: left;
  transition: border-color var(--transition), background var(--transition);
  min-height: 92px;
}

.chapter-card:hover,
.chapter-card.active {
  border-color: var(--color-border);
  background: var(--color-surface);
}

.card-label {
  margin-bottom: var(--space-2);
}

.card-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: 1.15rem;
  letter-spacing: 0.08em;
}

.reader-shell {
  max-width: var(--content-read);
  margin: 0 auto;
  padding: var(--space-6) var(--space-6) var(--space-12);
}

.reader-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: var(--space-4);
}

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  padding: 0.7rem 1rem;
  color: var(--color-text-muted);
  border-radius: 999px;
  border: 1px solid var(--color-divider);
  background: var(--color-surface);
}

.chapter-nav-arrows {
  display: flex;
  gap: var(--space-2);
}

.chapter-nav-arrows button {
  width: 42px;
  height: 42px;
  border-radius: 999px;
  color: var(--color-text-muted);
  background: var(--color-surface);
  border: 1px solid var(--color-divider);
}

.chapter-nav-arrows button:disabled,
.footer-nav-btn:disabled {
  opacity: 0.38;
  cursor: default;
  transform: none;
}

.reader-body {
  padding-top: var(--space-6);
}

.chapter-heading {
  padding-bottom: var(--space-5);
  border-bottom: 1px solid var(--color-divider);
}

.chapter-meta-line {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-bottom: var(--space-3);
}

.chapter-title {
  margin: 0;
  font-family: var(--font-display);
  font-size: clamp(1.9rem, 1.45rem + 2vw, 2.8rem);
  letter-spacing: 0.12em;
  font-weight: 300;
}

.reader-toggles {
  display: flex;
  flex-wrap: wrap;
  gap: var(--space-2);
  margin-top: var(--space-4);
}

.toggle-chip {
  border: 1px solid var(--color-divider);
  white-space: nowrap;
}

.toggle-chip.active {
  color: var(--color-primary-strong);
  border-color: rgba(141, 82, 34, 0.22);
  background: rgba(141, 82, 34, 0.12);
}

.chapter-guide {
  padding: var(--space-4) 0;
  border-bottom: 1px solid var(--color-divider);
}

.chapter-guide-summary {
  margin: 0;
  color: var(--color-text-muted);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  line-height: 1.85;
}

.chapter-guide-list {
  margin: var(--space-3) 0 0;
  padding-left: 1.1rem;
  color: var(--color-text);
}

.chapter-guide-list li + li {
  margin-top: var(--space-2);
}

.chapter-text {
  margin-top: var(--space-6);
  display: grid;
  gap: 0;
}

.para-card {
  padding: var(--space-5) 0;
  border-bottom: 1px solid var(--color-divider);
  scroll-margin-top: 7rem;
}

.para-content {
  min-width: 0;
}

.para-original {
  margin: 0;
  font-size: var(--text-base);
  line-height: 2.05;
  text-indent: 2em;
}

.para-addon {
  margin-top: var(--space-4);
  padding: var(--space-3) 0 0;
  border-radius: var(--radius-md);
  border-top: 1px dashed var(--color-divider);
  background: transparent;
}

.addon-label {
  display: inline-flex;
  margin-bottom: var(--space-2);
  font-family: var(--font-sans);
  font-size: var(--text-xs);
  letter-spacing: 0.08em;
  color: var(--color-primary-strong);
}

.para-addon p {
  margin: 0;
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  line-height: 1.9;
  color: var(--color-text);
}

.anno {
  display: inline;
  padding: 0;
  border: 0;
  background: none;
  color: var(--color-primary);
  border-bottom: 1px dotted currentColor;
  cursor: pointer;
}

.anno:hover,
.anno:focus-visible {
  color: var(--color-primary-strong);
}

.reader-footer {
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--color-divider);
  display: flex;
  justify-content: space-between;
  gap: var(--space-3);
}

.footer-nav-btn {
  padding: 0.75rem 1rem;
  border-radius: 999px;
  border: 1px solid var(--color-divider);
  background: transparent;
  color: var(--color-text-muted);
  min-height: 44px;
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.tooltip-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.36);
  z-index: 90;
}

.tooltip {
  position: fixed;
  z-index: 100;
  max-width: 320px;
  padding: var(--space-4);
  border-radius: var(--radius-lg);
  border: 1px solid var(--color-divider);
  background: color-mix(in srgb, var(--color-bg-2) 96%, transparent);
  box-shadow: 0 30px 80px -32px var(--color-shadow);
  opacity: 0;
  pointer-events: none;
  transform: translateY(6px);
  transition: opacity var(--transition), transform var(--transition);
  max-height: min(72dvh, 560px);
  overflow: auto;
}

.tooltip.visible {
  opacity: 1;
  transform: translateY(0);
}

.tooltip-header {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: var(--space-3);
}

.tooltip-word {
  font-family: var(--font-display);
  font-size: var(--text-lg);
}

.tooltip-pinyin {
  margin-top: var(--space-1);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  color: var(--color-primary-strong);
}

.tooltip-meaning {
  margin-top: var(--space-3);
  font-family: var(--font-sans);
  font-size: var(--text-sm);
  line-height: 1.75;
  color: var(--color-text-muted);
}

.tooltip-close {
  display: none;
  width: 32px;
  height: 32px;
  border-radius: 999px;
  background: var(--color-surface-soft);
  color: var(--color-text-muted);
}

.site-footer {
  max-width: var(--content-wide);
  margin: 0 auto;
  padding: var(--space-8) var(--space-6);
  border-top: 1px solid var(--color-divider);
  text-align: center;
  color: var(--color-text-soft);
  font-family: var(--font-sans);
  font-size: var(--text-xs);
}

.site-footer p {
  margin: 0;
}

.site-footer p + p {
  margin-top: var(--space-2);
}

@media (max-width: 980px) {
  .chapter-grid {
    grid-template-columns: repeat(3, minmax(0, 1fr));
  }
}

@media (max-width: 720px) {
  .header-inner,
  .home-content,
  .reader-shell,
  .site-footer {
    padding-left: var(--space-4);
    padding-right: var(--space-4);
  }

  .logo-subtext {
    display: none;
  }

  .nav-panel {
    position: fixed;
    top: 0;
    right: 0;
    width: 100vw;
    height: 100dvh;
    max-height: none;
    border-radius: 0;
    border-left: 0;
    border-right: 0;
    border-top: 0;
    border-bottom: 0;
    transform: translateX(100%);
    opacity: 1;
    pointer-events: none;
    padding: var(--space-4);
    padding-top: calc(var(--space-4) + env(safe-area-inset-top));
  }

  .nav-panel.open {
    transform: translateX(0);
    pointer-events: auto;
  }

  .nav-close {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }

  .home-content {
    padding-top: var(--space-10);
  }

  .home-title {
    letter-spacing: 0.14em;
  }

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

  .reader-header {
    align-items: stretch;
    gap: var(--space-3);
  }

  .chapter-title {
    letter-spacing: 0.08em;
    line-height: 1.25;
  }

  .reader-shell {
    padding-bottom: calc(7rem + env(safe-area-inset-bottom));
  }

  .reader-body {
    padding-top: var(--space-4);
  }

  .reader-toggles {
    position: sticky;
    top: 4.4rem;
    z-index: 8;
    margin-top: var(--space-3);
    padding: var(--space-2) 0;
    background: var(--color-bg);
    flex-wrap: nowrap;
    overflow-x: auto;
    scrollbar-width: none;
  }

  .reader-toggles::-webkit-scrollbar {
    display: none;
  }

  .chapter-guide {
    padding: var(--space-3) 0;
  }

  .para-card {
    padding: var(--space-4) 0;
  }

  .para-original {
    font-size: 1.04rem;
    text-indent: 1.7em;
    line-height: 2.12;
  }

  .para-addon p,
  .chapter-guide-summary {
    font-size: 0.96rem;
    line-height: 1.95;
  }

  .reader-footer {
    position: fixed;
    left: 0;
    right: 0;
    bottom: 0;
    z-index: 20;
    margin-top: 0;
    padding: var(--space-3) var(--space-4);
    padding-bottom: calc(var(--space-3) + env(safe-area-inset-bottom));
    background: color-mix(in srgb, var(--color-bg) 96%, transparent);
    border-top: 1px solid var(--color-divider);
    backdrop-filter: blur(16px);
    -webkit-backdrop-filter: blur(16px);
    display: grid;
    grid-template-columns: minmax(0, 1fr) auto minmax(0, 1fr);
    align-items: center;
    gap: var(--space-2);
  }

  .tooltip {
    left: 0 !important;
    right: 0 !important;
    bottom: 0;
    top: auto !important;
    max-width: none;
    width: 100%;
    border-radius: 1.2rem 1.2rem 0 0;
    pointer-events: auto;
    transform: translateY(100%);
    padding-bottom: calc(var(--space-5) + env(safe-area-inset-bottom));
    max-height: 68dvh;
  }

  .tooltip.visible {
    transform: translateY(0);
  }

  .tooltip-close {
    display: inline-flex;
    align-items: center;
    justify-content: center;
  }
}

@media print {
  .site-header,
  .reader-header,
  .reader-footer,
  .tooltip,
  .tooltip-backdrop,
  .nav {
    display: none !important;
  }

  .home {
    display: none !important;
  }

  .reader {
    display: block !important;
  }

  .reader-shell {
    padding: 0;
  }

  .para-card {
    break-inside: avoid;
    box-shadow: none;
  }
}