:root {
  --font-size-reader: 20px;
  --line-height-reader: 1.85;
  --font-family-reader: 'Lora', Georgia, 'Times New Roman', serif;
}

html[data-font="serif"] {
  --font-family-reader: 'Lora', Georgia, serif;
}
html[data-font="merriweather"] {
  --font-family-reader: 'Merriweather', Georgia, serif;
}
html[data-font="sans"] {
  --font-family-reader: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
}

/* Dark Theme (Default) */
html[data-theme="dark"] {
  --bg-page: #111418;
  --bg-card: #181c22;
  --bg-topbar: rgba(24, 28, 34, 0.92);
  --bg-elevated: #222831;
  --text-main: #d8dee9;
  --text-heading: #eceff4;
  --text-muted: #8b95a5;
  --border-color: #2b323d;
  --accent: #38bdf8;
  --accent-soft: rgba(56, 189, 248, 0.14);
}

/* Sepia Theme */
html[data-theme="sepia"] {
  --bg-page: #ece2d0;
  --bg-card: #f6efe2;
  --bg-topbar: rgba(246, 239, 226, 0.94);
  --bg-elevated: #e5d9c3;
  --text-main: #3b2f2f;
  --text-heading: #241915;
  --text-muted: #786655;
  --border-color: #d5c5ab;
  --accent: #9c4221;
  --accent-soft: rgba(156, 66, 33, 0.12);
}

/* Light Theme */
html[data-theme="light"] {
  --bg-page: #f3f4f6;
  --bg-card: #ffffff;
  --bg-topbar: rgba(255, 255, 255, 0.94);
  --bg-elevated: #e5e7eb;
  --text-main: #1f2937;
  --text-heading: #111827;
  --text-muted: #6b7280;
  --border-color: #e5e7eb;
  --accent: #0284c7;
  --accent-soft: rgba(2, 132, 199, 0.1);
}

* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
}

body {
  background-color: var(--bg-page);
  color: var(--text-main);
  font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  transition: background-color 0.2s ease, color 0.2s ease;
  min-height: 100vh;
}

#progress-bar-container {
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 3px;
  background: transparent;
  z-index: 200;
}

#progress-bar {
  height: 100%;
  width: 0%;
  background: var(--accent);
  transition: width 0.1s ease-out;
}

.topbar {
  position: sticky;
  top: 0;
  z-index: 100;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.6rem 1.25rem;
  background: var(--bg-topbar);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border-color);
  gap: 0.75rem;
}

.topbar-left, .topbar-right {
  display: flex;
  align-items: center;
  gap: 0.5rem;
}

.topbar-center {
  flex: 1;
  text-align: center;
  font-size: 0.9rem;
  font-weight: 500;
  color: var(--text-muted);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  max-width: 420px;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  gap: 0.4rem;
  background: var(--bg-elevated);
  color: var(--text-main);
  border: 1px solid var(--border-color);
  border-radius: 8px;
  padding: 0.45rem 0.75rem;
  font-size: 0.85rem;
  font-weight: 500;
  cursor: pointer;
  text-decoration: none;
  transition: all 0.15s ease;
}

.icon-btn:hover {
  border-color: var(--accent);
  color: var(--accent);
}

.epub-btn {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: transparent;
}

.book-switcher {
  display: inline-flex;
  background: var(--bg-elevated);
  padding: 3px;
  border-radius: 8px;
  border: 1px solid var(--border-color);
}

.book-tab {
  background: transparent;
  border: none;
  color: var(--text-muted);
  padding: 0.35rem 0.7rem;
  font-size: 0.8rem;
  font-weight: 600;
  border-radius: 6px;
  cursor: pointer;
  transition: all 0.15s ease;
}

.book-tab.active {
  background: var(--bg-card);
  color: var(--accent);
  box-shadow: 0 1px 3px rgba(0,0,0,0.15);
}

/* Settings Panel */
.settings-panel {
  position: fixed;
  top: 3.6rem;
  right: 1.25rem;
  width: 310px;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 12px;
  padding: 1rem;
  z-index: 150;
  box-shadow: 0 12px 32px rgba(0, 0, 0, 0.35);
}

.settings-panel.hidden {
  display: none;
}

.setting-row {
  margin-bottom: 0.9rem;
}

.setting-row:last-child {
  margin-bottom: 0;
}

.setting-label {
  display: block;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  margin-bottom: 0.45rem;
}

.theme-group, .font-group, .size-group {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 0.4rem;
}

.theme-btn, .font-btn, .size-btn {
  padding: 0.45rem 0.4rem;
  font-size: 0.8rem;
  font-weight: 500;
  border-radius: 6px;
  border: 1px solid var(--border-color);
  background: var(--bg-elevated);
  color: var(--text-main);
  cursor: pointer;
}

.theme-btn.active, .font-btn.active {
  border-color: var(--accent);
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}

/* Drawer TOC */
.drawer-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.55);
  z-index: 160;
}

.drawer-overlay.hidden {
  display: none;
}

.toc-drawer {
  position: fixed;
  top: 0;
  left: 0;
  bottom: 0;
  width: min(380px, 90vw);
  background: var(--bg-card);
  border-right: 1px solid var(--border-color);
  z-index: 170;
  display: flex;
  flex-direction: column;
  transform: translateX(-100%);
  transition: transform 0.25s cubic-bezier(0.16, 1, 0.3, 1);
}

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

.drawer-header {
  display: flex;
  justify-content: space-between;
  align-items: flex-start;
  padding: 1.1rem 1.2rem;
  border-bottom: 1px solid var(--border-color);
}

.drawer-header h2 {
  font-size: 1rem;
  color: var(--text-heading);
  margin-bottom: 0.2rem;
}

.drawer-header p {
  font-size: 0.78rem;
  color: var(--text-muted);
}

.drawer-search {
  padding: 0.75rem 1.2rem;
  border-bottom: 1px solid var(--border-color);
}

.drawer-search input {
  width: 100%;
  padding: 0.55rem 0.8rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background: var(--bg-elevated);
  color: var(--text-main);
  font-size: 0.88rem;
  outline: none;
}

.drawer-search input:focus {
  border-color: var(--accent);
}

.toc-list {
  flex: 1;
  overflow-y: auto;
  padding: 0.75rem 1rem 2rem;
}

.vol-section {
  margin-bottom: 1rem;
}

.vol-header {
  font-size: 0.82rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 0.03em;
  color: var(--accent);
  padding: 0.4rem 0.5rem;
  margin-bottom: 0.3rem;
  border-bottom: 1px solid var(--border-color);
}

.toc-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  width: 100%;
  text-align: left;
  background: transparent;
  border: none;
  color: var(--text-main);
  padding: 0.55rem 0.65rem;
  border-radius: 7px;
  font-size: 0.88rem;
  cursor: pointer;
  transition: background 0.12s;
  gap: 0.5rem;
}

.toc-item:hover {
  background: var(--bg-elevated);
}

.toc-item.active {
  background: var(--accent-soft);
  color: var(--accent);
  font-weight: 600;
}

.toc-item-title {
  flex: 1;
  line-height: 1.35;
}

.toc-item-words {
  font-size: 0.72rem;
  color: var(--text-muted);
  white-space: nowrap;
}

/* Reader Main Layout */
.reader-container {
  max-width: 820px;
  margin: 1.5rem auto 4rem;
  padding: 0 1rem;
}

.chapter-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: 14px;
  padding: 2.5rem 3rem;
  box-shadow: 0 4px 20px rgba(0, 0, 0, 0.08);
}

.chapter-meta-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 0.8rem;
  flex-wrap: wrap;
  gap: 0.5rem;
}

.book-badge {
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--accent);
  background: var(--accent-soft);
  padding: 0.25rem 0.65rem;
  border-radius: 99px;
}

.word-count-badge {
  font-size: 0.8rem;
  color: var(--text-muted);
}

.chapter-title {
  font-family: var(--font-family-reader);
  font-size: 1.65rem;
  line-height: 1.35;
  color: var(--text-heading);
  margin-bottom: 1.5rem;
}

.chapter-nav-top, .chapter-nav-bottom {
  display: flex;
  justify-content: space-between;
  gap: 0.65rem;
  margin: 1.5rem 0;
}

.chapter-nav-bottom {
  margin-top: 2.5rem;
  padding-top: 1.75rem;
  border-top: 1px solid var(--border-color);
}

.nav-btn {
  flex: 1;
  padding: 0.6rem 0.9rem;
  border-radius: 8px;
  border: 1px solid var(--border-color);
  background: var(--bg-elevated);
  color: var(--text-main);
  font-size: 0.88rem;
  font-weight: 500;
  cursor: pointer;
  transition: all 0.15s ease;
}

.nav-btn:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
}

.nav-btn:disabled {
  opacity: 0.4;
  cursor: not-allowed;
}

.nav-btn-large {
  padding: 0.85rem 1.1rem;
  font-size: 0.95rem;
  font-weight: 600;
}

.nav-btn-primary {
  background: var(--accent-soft);
  color: var(--accent);
  border-color: var(--accent);
}

/* Prose Content */
.chapter-content {
  font-family: var(--font-family-reader);
  font-size: var(--font-size-reader);
  line-height: var(--line-height-reader);
  color: var(--text-main);
  margin-top: 1.75rem;
}

.chapter-content p {
  margin-bottom: 1.15em;
  text-align: justify;
  text-indent: 1.5em;
}

.chapter-content h2 {
  font-size: 1.2em;
  color: var(--text-heading);
  margin: 1.8em 0 0.9em;
}

.chapter-content hr.scene-break {
  border: none;
  text-align: center;
  margin: 2em 0;
  color: var(--text-muted);
}

.chapter-content hr.scene-break::after {
  content: "✦   ✦   ✦";
  font-size: 0.85em;
  letter-spacing: 0.4em;
}

/* Mobile responsiveness */
@media (max-width: 680px) {
  .topbar {
    padding: 0.5rem 0.75rem;
  }
  .topbar-center, .btn-label {
    display: none;
  }
  .chapter-card {
    padding: 1.4rem 1.15rem;
    border-radius: 10px;
  }
  .chapter-title {
    font-size: 1.35rem;
  }
  .chapter-content p {
    text-align: left;
    text-indent: 1.2em;
  }
}