/* ===== Design Tokens ===== */
:root {
  --font-display: 'ZCOOL XiaoWei', 'Noto Serif SC', 'Songti SC', serif;
  --font-body: 'Noto Serif SC', 'Songti SC', 'SimSun', serif;

  --text-xs:   clamp(0.8rem, 0.74rem + 0.28vw, 0.92rem);
  --text-sm:   clamp(0.94rem, 0.88rem + 0.3vw, 1.06rem);
  --text-base: clamp(1.06rem, 0.98rem + 0.38vw, 1.22rem);
  --text-lg:   clamp(1.22rem, 1.08rem + 0.62vw, 1.52rem);
  --text-xl:   clamp(1.58rem, 1.24rem + 1.15vw, 2.18rem);
  --text-2xl:  clamp(2rem, 1.4rem + 2.15vw, 3.2rem);
  --text-3xl:  clamp(2.45rem, 1.2rem + 3.8vw, 4.8rem);

  --space-1: 0.25rem;
  --space-2: 0.5rem;
  --space-3: 0.75rem;
  --space-4: 1rem;
  --space-6: 1.5rem;
  --space-8: 2rem;
  --space-10: 2.5rem;
  --space-12: 3rem;
  --space-16: 4rem;
  --space-20: 5rem;
  --space-24: 6rem;

  --radius-sm: 0.25rem;
  --radius-md: 0.5rem;
  --transition: 200ms ease;
  --sidebar-w: 260px;

  /* Light: warm rice paper palette */
  --color-bg: #f5f0e8;
  --color-surface: #faf6ee;
  --color-surface-2: #efe9dd;
  --color-border: #d8cdb8;
  --color-border-light: #e8dece;
  --color-text: #2c2416;
  --color-text-muted: #6b5d4a;
  --color-text-faint: #a89a84;
  --color-accent: #8b4513;
  --color-accent-light: #c2956a;
  --color-ruby: #9e3636;
  --color-seal: #b22222;
  --color-highlight: rgba(139, 69, 19, 0.06);
  --color-overlay: rgba(44, 36, 22, 0.5);
  --shadow-sm: 0 1px 3px rgba(44, 36, 22, 0.06);
  --shadow-md: 0 4px 12px rgba(44, 36, 22, 0.08);
}

[data-theme="dark"] {
  --color-bg: #1a1612;
  --color-surface: #211c17;
  --color-surface-2: #2a241d;
  --color-border: #3d3428;
  --color-border-light: #322b21;
  --color-text: #d4c8b4;
  --color-text-muted: #8a7d6b;
  --color-text-faint: #5a5044;
  --color-accent: #c2956a;
  --color-accent-light: #8b6a42;
  --color-ruby: #d47070;
  --color-seal: #c44444;
  --color-highlight: rgba(194, 149, 106, 0.08);
  --color-overlay: rgba(0, 0, 0, 0.6);
  --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --color-bg: #1a1612;
    --color-surface: #211c17;
    --color-surface-2: #2a241d;
    --color-border: #3d3428;
    --color-border-light: #322b21;
    --color-text: #d4c8b4;
    --color-text-muted: #8a7d6b;
    --color-text-faint: #5a5044;
    --color-accent: #c2956a;
    --color-accent-light: #8b6a42;
    --color-ruby: #d47070;
    --color-seal: #c44444;
    --color-highlight: rgba(194, 149, 106, 0.08);
    --color-overlay: rgba(0, 0, 0, 0.6);
    --shadow-sm: 0 1px 3px rgba(0,0,0,0.2);
    --shadow-md: 0 4px 12px rgba(0,0,0,0.3);
  }
}

/* ===== Reset & Base ===== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
  scroll-behavior: smooth;
  hanging-punctuation: first last;
}

body {
  min-height: 100dvh;
  font-family: var(--font-body);
  font-size: var(--text-base);
  line-height: 1.85;
  color: var(--color-text);
  background: var(--color-bg);
  overflow-x: hidden;
}

button { cursor: pointer; background: none; border: none; font: inherit; color: inherit; }
a { color: inherit; text-decoration: none; }
input { font: inherit; color: inherit; }

::selection {
  background: rgba(139, 69, 19, 0.15);
  color: var(--color-text);
}

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

/* ===== App Layout ===== */
#app {
  display: flex;
  min-height: 100dvh;
}

/* ===== Sidebar ===== */
.sidebar {
  width: var(--sidebar-w);
  height: 100dvh;
  position: fixed;
  left: 0; top: 0;
  background: var(--color-surface);
  border-right: 1px solid var(--color-border-light);
  display: flex;
  flex-direction: column;
  z-index: 100;
  overflow: hidden;
}

.sidebar-header {
  padding: var(--space-6) var(--space-6) var(--space-3);
  text-align: center;
  border-bottom: 1px solid var(--color-border-light);
}

.logo {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 400;
  letter-spacing: 0.25em;
  color: var(--color-accent);
  cursor: pointer;
  transition: color var(--transition);
}
.logo:hover { color: var(--color-seal); }

.logo-sub {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  letter-spacing: 0.5em;
  margin-top: var(--space-1);
}

.sidebar-search {
  padding: var(--space-3) var(--space-4);
}

.sidebar-search input {
  width: 100%;
  padding: var(--space-2) var(--space-3);
  background: var(--color-bg);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-sm);
  font-size: var(--text-xs);
  transition: border-color var(--transition);
}
.sidebar-search input::placeholder { color: var(--color-text-faint); }
.sidebar-search input:focus {
  border-color: var(--color-accent-light);
  outline: none;
}

.sidebar-toc {
  flex: 1;
  overflow-y: auto;
  padding: var(--space-2) 0;
  scrollbar-width: thin;
  scrollbar-color: var(--color-border) transparent;
}

.toc-section {
  margin-bottom: var(--space-1);
}

.toc-section-title {
  display: flex;
  align-items: center;
  gap: var(--space-2);
  padding: var(--space-2) var(--space-4);
  font-size: var(--text-sm);
  font-weight: 500;
  color: var(--color-text-muted);
  cursor: pointer;
  transition: color var(--transition), background var(--transition);
  user-select: none;
}
.toc-section-title:hover {
  color: var(--color-accent);
  background: var(--color-highlight);
}
.toc-section-title .arrow {
  font-size: 0.6em;
  transition: transform var(--transition);
  color: var(--color-text-faint);
}
.toc-section-title.open .arrow {
  transform: rotate(90deg);
}

.toc-subsection {
  display: none;
}
.toc-subsection.open { display: block; }

.toc-sub-title {
  padding: var(--space-1) var(--space-4) var(--space-1) var(--space-8);
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  letter-spacing: 0.1em;
}

.toc-poem {
  display: block;
  padding: var(--space-1) var(--space-4) var(--space-1) var(--space-10);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  cursor: pointer;
  transition: all var(--transition);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}
.toc-poem:hover {
  color: var(--color-accent);
  background: var(--color-highlight);
}
.toc-poem.active {
  color: var(--color-accent);
  background: var(--color-highlight);
  font-weight: 500;
}

.sidebar-footer {
  padding: var(--space-3) var(--space-4);
  border-top: 1px solid var(--color-border-light);
  text-align: center;
}
.sidebar-footer p {
  font-size: 0.65rem;
  color: var(--color-text-faint);
}

/* ===== Mobile Header ===== */
.mobile-header {
  display: none;
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 48px;
  background: var(--color-surface);
  border-bottom: 1px solid var(--color-border-light);
  z-index: 90;
  align-items: center;
  padding: 0 var(--space-3);
  gap: var(--space-3);
}

.mobile-title {
  flex: 1;
  text-align: center;
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--color-accent);
  letter-spacing: 0.2em;
}

.menu-btn, .theme-btn {
  width: 36px; height: 36px;
  display: flex; align-items: center; justify-content: center;
  border-radius: var(--radius-sm);
  color: var(--color-text-muted);
  transition: all var(--transition);
}
.menu-btn:hover, .theme-btn:hover {
  background: var(--color-highlight);
  color: var(--color-accent);
}

.overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--color-overlay);
  z-index: 99;
  opacity: 0;
  transition: opacity 300ms ease;
}
.overlay.active { display: block; opacity: 1; }

/* ===== Main ===== */
.main {
  margin-left: var(--sidebar-w);
  flex: 1;
  min-height: 100dvh;
}

.view { display: none; }
.view.active { display: block; }

/* ===== Home View ===== */
.home-content {
  max-width: 640px;
  margin: 0 auto;
  padding: var(--space-16) var(--space-6) var(--space-12);
  text-align: center;
}

.home-seal {
  width: 72px; height: 72px;
  margin: 0 auto var(--space-6);
  display: flex; align-items: center; justify-content: center;
  font-family: var(--font-display);
  font-size: 2rem;
  color: var(--color-seal);
  border: 2px solid var(--color-seal);
  border-radius: 4px;
  transform: rotate(-3deg);
  opacity: 0.9;
}

.home-title {
  font-family: var(--font-display);
  font-size: var(--text-3xl);
  font-weight: 400;
  letter-spacing: 0.4em;
  color: var(--color-text);
  margin-bottom: var(--space-2);
}

.home-subtitle {
  font-size: var(--text-sm);
  color: var(--color-text-faint);
  letter-spacing: 1em;
  margin-bottom: var(--space-8);
}

.home-desc {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 1.8;
  margin-bottom: var(--space-10);
  max-width: 400px;
  margin-left: auto;
  margin-right: auto;
}

.home-sections {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(140px, 1fr));
  gap: var(--space-3);
  margin-bottom: var(--space-12);
}

.home-section-card {
  padding: var(--space-6) var(--space-4);
  background: var(--color-surface);
  border: 1px solid var(--color-border-light);
  border-radius: var(--radius-md);
  cursor: pointer;
  transition: all var(--transition);
  text-align: center;
}
.home-section-card:hover {
  border-color: var(--color-accent-light);
  box-shadow: var(--shadow-md);
  transform: translateY(-2px);
}

.home-section-card .card-name {
  font-family: var(--font-display);
  font-size: var(--text-lg);
  color: var(--color-text);
  letter-spacing: 0.15em;
  margin-bottom: var(--space-2);
}

.home-section-card .card-count {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.home-quote {
  margin-top: var(--space-4);
  padding-top: var(--space-8);
  border-top: 1px solid var(--color-border-light);
}
.home-quote p {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  font-style: italic;
  line-height: 2;
}
.home-quote cite {
  display: block;
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  font-style: normal;
  margin-top: var(--space-2);
}

/* ===== Section View ===== */
.section-content {
  max-width: 720px;
  margin: 0 auto;
  padding: var(--space-8) var(--space-6) var(--space-12);
}

.section-title {
  font-family: var(--font-display);
  font-size: var(--text-xl);
  font-weight: 400;
  letter-spacing: 0.2em;
  text-align: center;
  margin-bottom: var(--space-8);
  padding-bottom: var(--space-4);
  border-bottom: 1px solid var(--color-border-light);
}

.section-sub {
  margin-bottom: var(--space-6);
}
.section-sub-title {
  font-size: var(--text-sm);
  color: var(--color-text-faint);
  letter-spacing: 0.2em;
  margin-bottom: var(--space-3);
  padding-left: var(--space-1);
}

.section-grid {
  display: flex;
  flex-direction: column;
  gap: var(--space-8);
}

.section-poems {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(100px, 1fr));
  gap: var(--space-2);
}

.section-poem-link {
  padding: var(--space-3) var(--space-2);
  text-align: center;
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  border: 1px solid transparent;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: all var(--transition);
  letter-spacing: 0.05em;
}
.section-poem-link:hover {
  color: var(--color-accent);
  border-color: var(--color-border-light);
  background: var(--color-highlight);
}

/* ===== Poem View ===== */
.poem-content {
  max-width: 640px;
  margin: 0 auto;
  padding: var(--space-8) var(--space-6) var(--space-16);
}

.poem-nav-top {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: var(--space-6);
}

.back-btn {
  display: inline-flex;
  align-items: center;
  gap: var(--space-2);
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  transition: color var(--transition);
  padding: var(--space-1) 0;
}
.back-btn:hover { color: var(--color-accent); }

.poem-position {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
}

.poem-header {
  text-align: center;
  margin-bottom: var(--space-8);
  padding-bottom: var(--space-6);
  border-bottom: 1px solid var(--color-border-light);
}

.poem-section-label {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  letter-spacing: 0.3em;
  margin-bottom: var(--space-3);
}

.poem-title {
  font-family: var(--font-display);
  font-size: var(--text-2xl);
  font-weight: 400;
  letter-spacing: 0.25em;
  color: var(--color-text);
}

.poem-body {
  margin-bottom: var(--space-8);
}

.stanza {
  margin-bottom: var(--space-6);
  text-align: center;
}
.stanza:last-child { margin-bottom: 0; }

.poem-line {
  font-size: var(--text-base);
  line-height: 2.4;
  color: var(--color-text);
  letter-spacing: 0.08em;
}

/* Ruby annotations for rare characters */
ruby {
  ruby-align: center;
}
ruby rt {
  font-size: 0.5em;
  color: var(--color-ruby);
  font-family: var(--font-body);
  font-weight: 300;
  letter-spacing: 0;
}

/* ===== Notes ===== */
.poem-notes {
  margin-top: var(--space-8);
  padding-top: var(--space-6);
  border-top: 1px solid var(--color-border-light);
}

.poem-notes-title {
  font-size: var(--text-xs);
  color: var(--color-text-faint);
  letter-spacing: 0.3em;
  margin-bottom: var(--space-3);
  text-align: center;
}

.poem-notes-text {
  font-size: var(--text-sm);
  color: var(--color-text-muted);
  line-height: 2;
  text-align: center;
  max-width: 500px;
  margin: 0 auto;
}

/* ===== Poem Nav Bottom ===== */
.poem-nav-bottom {
  display: flex;
  justify-content: space-between;
  margin-top: var(--space-10);
  padding-top: var(--space-6);
  border-top: 1px solid var(--color-border-light);
}

.nav-link {
  font-size: var(--text-xs);
  color: var(--color-text-muted);
  cursor: pointer;
  display: flex;
  align-items: center;
  gap: var(--space-2);
  transition: color var(--transition);
  max-width: 45%;
}
.nav-link:hover { color: var(--color-accent); }
.nav-link.prev { text-align: left; }
.nav-link.next { text-align: right; margin-left: auto; }
.nav-link .nav-label {
  font-size: 0.65rem;
  color: var(--color-text-faint);
  display: block;
}
.nav-link .nav-title {
  letter-spacing: 0.1em;
}

/* ===== Responsive ===== */
@media (max-width: 768px) {
  :root {
    --text-xs: clamp(0.92rem, 0.86rem + 0.35vw, 1rem);
    --text-sm: clamp(1.02rem, 0.96rem + 0.45vw, 1.16rem);
    --text-base: clamp(1.16rem, 1.06rem + 0.7vw, 1.34rem);
    --text-lg: clamp(1.34rem, 1.18rem + 1vw, 1.72rem);
    --text-xl: clamp(1.78rem, 1.42rem + 1.9vw, 2.38rem);
    --text-2xl: clamp(2.12rem, 1.66rem + 2.4vw, 2.92rem);
  }

  body {
    line-height: 1.95;
  }

  .sidebar {
    transform: translateX(-100%);
    transition: transform 300ms cubic-bezier(0.16, 1, 0.3, 1);
    width: 280px;
  }
  .sidebar.open { transform: translateX(0); }

  .mobile-header { display: flex; }

  .main {
    margin-left: 0;
    padding-top: 48px;
  }

  .home-content {
    padding: var(--space-10) var(--space-4) var(--space-8);
  }

  .home-seal {
    width: 56px; height: 56px;
    font-size: 1.6rem;
  }

  .poem-content,
  .section-content {
    padding-left: var(--space-4);
    padding-right: var(--space-4);
  }

  .poem-line {
    line-height: 2.55;
  }

  ruby rt {
    font-size: 0.56em;
  }

  .section-poems {
    grid-template-columns: repeat(auto-fill, minmax(80px, 1fr));
  }
}

/* Desktop theme toggle in sidebar */
@media (min-width: 769px) {
  .sidebar-header {
    position: relative;
  }
  .theme-btn.desktop-theme {
    position: absolute;
    top: var(--space-3);
    right: var(--space-3);
    width: 28px; height: 28px;
  }
}

/* Scrollbar styling */
.sidebar-toc::-webkit-scrollbar { width: 4px; }
.sidebar-toc::-webkit-scrollbar-track { background: transparent; }
.sidebar-toc::-webkit-scrollbar-thumb { background: var(--color-border); border-radius: 2px; }

/* Animations */
@keyframes fadeIn {
  from { opacity: 0; transform: translateY(8px); }
  to { opacity: 1; transform: translateY(0); }
}

.view.active {
  animation: fadeIn 300ms ease;
}

/* Print styles */
@media print {
  .sidebar, .mobile-header, .back-btn, .poem-nav-bottom { display: none !important; }
  .main { margin-left: 0 !important; }
  .poem-line { font-size: 14pt; }
}