@import url('https://fonts.googleapis.com/css2?family=Inter:wght@300;400;500;600;700&display=swap');

/* ==================== DESIGN TOKENS ==================== */
:root {
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --radius-sm: 8px;
  --radius-md: 14px;
  --radius-lg: 20px;
  --radius-full: 50%;
  --shadow-sm: 0 1px 3px rgba(0,0,0,.08);
  --shadow-md: 0 4px 16px rgba(0,0,0,.1);
  --shadow-lg: 0 8px 32px rgba(0,0,0,.15);
  --transition-fast: 180ms cubic-bezier(.4,0,.2,1);
  --transition-normal: 300ms cubic-bezier(.4,0,.2,1);
  --transition-slow: 500ms cubic-bezier(.4,0,.2,1);
  --z-header: 100;
  --z-sidebar: 200;
  --z-overlay: 300;
  --z-modal: 400;
}

/* ==================== LIGHT THEME ==================== */
[data-theme="light"] {
  --bg-primary: #F5F5F5;
  --bg-surface: #FFFFFF;
  --bg-surface-hover: #F0F0F0;
  --bg-elevated: #FFFFFF;
  --text-primary: #1A1A1A;
  --text-secondary: #6B7280;
  --text-muted: #9CA3AF;
  --accent: #6366F1;
  --accent-hover: #4F46E5;
  --accent-soft: rgba(99,102,241,.1);
  --border: #E5E7EB;
  --border-subtle: #F3F4F6;
  --progress-bg: #E5E7EB;
  --progress-fill: #6366F1;
  --glass-bg: rgba(255,255,255,.7);
  --glass-border: rgba(255,255,255,.3);
  --canvas-filter: none;
  --scrollbar-thumb: #D1D5DB;
  --scrollbar-track: transparent;
  --card-shadow: 0 1px 3px rgba(0,0,0,.06), 0 4px 12px rgba(0,0,0,.04);
}

/* ==================== AMOLED DARK THEME ==================== */
[data-theme="dark"] {
  --bg-primary: #000000;
  --bg-surface: #0A0A0A;
  --bg-surface-hover: #141414;
  --bg-elevated: #111111;
  --text-primary: #FFFFFF;
  --text-secondary: #A1A1AA;
  --text-muted: #71717A;
  --accent: #818CF8;
  --accent-hover: #6366F1;
  --accent-soft: rgba(129,140,248,.12);
  --border: #1E1E1E;
  --border-subtle: #141414;
  --progress-bg: #1E1E1E;
  --progress-fill: #818CF8;
  --glass-bg: rgba(10,10,10,.8);
  --glass-border: rgba(255,255,255,.06);
  --canvas-filter: none;
  --scrollbar-thumb: #333;
  --scrollbar-track: transparent;
  --card-shadow: 0 1px 3px rgba(0,0,0,.3), 0 4px 12px rgba(0,0,0,.2);
}

[data-theme="dark"][data-invert-pdf="true"] {
  --canvas-filter: invert(1) hue-rotate(180deg);
}

/* ==================== GLOBAL RESET ==================== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

html {
  font-family: var(--font-family);
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  scroll-behavior: smooth;
}

body {
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  transition: background var(--transition-normal), color var(--transition-normal);
  overflow-x: hidden;
}

/* ==================== SCROLLBAR ==================== */
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--scrollbar-track); }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: 3px; }
::-webkit-scrollbar-thumb:hover { background: var(--accent); }

/* ==================== HEADER ==================== */
.app-header {
  position: fixed;
  top: 0; left: 0; right: 0;
  height: 64px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 24px;
  background: var(--glass-bg);
  backdrop-filter: blur(20px) saturate(1.4);
  -webkit-backdrop-filter: blur(20px) saturate(1.4);
  border-bottom: 1px solid var(--glass-border);
  z-index: var(--z-header);
  transition: background var(--transition-normal);
}

.app-header .logo {
  display: flex;
  align-items: center;
  gap: 12px;
  font-weight: 700;
  font-size: 1.3rem;
  color: var(--text-primary);
  text-decoration: none;
}

.app-header .logo svg { width: 28px; height: 28px; }

.header-actions {
  display: flex;
  align-items: center;
  gap: 8px;
}

/* ==================== BUTTONS ==================== */
.btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 10px 20px;
  border: none;
  border-radius: var(--radius-sm);
  font-family: var(--font-family);
  font-size: .875rem;
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  text-decoration: none;
  white-space: nowrap;
}

.btn-primary {
  background: var(--accent);
  color: #FFF;
}
.btn-primary:hover { background: var(--accent-hover); transform: translateY(-1px); box-shadow: var(--shadow-md); }

.btn-ghost {
  background: transparent;
  color: var(--text-secondary);
  padding: 8px;
  border-radius: var(--radius-full);
}
.btn-ghost:hover { background: var(--accent-soft); color: var(--accent); }

.btn-icon {
  width: 40px; height: 40px;
  padding: 0;
  border-radius: var(--radius-full);
  background: var(--bg-surface);
  color: var(--text-secondary);
  border: 1px solid var(--border);
}
.btn-icon:hover { background: var(--accent-soft); color: var(--accent); border-color: var(--accent); }

.btn svg { width: 18px; height: 18px; }

/* ==================== LIBRARY VIEW ==================== */
#library-view {
  padding: 88px 24px 40px;
  max-width: 1400px;
  margin: 0 auto;
}

.library-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 32px;
}

.library-header h2 {
  font-size: 1.75rem;
  font-weight: 700;
  color: var(--text-primary);
}

.library-stats {
  font-size: .875rem;
  color: var(--text-muted);
}

/* Book Grid */
.book-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(180px, 1fr));
  gap: 24px;
}

.book-card {
  position: relative;
  background: var(--bg-surface);
  border-radius: var(--radius-md);
  border: 1px solid var(--border);
  overflow: hidden;
  cursor: pointer;
  transition: all var(--transition-normal);
  box-shadow: var(--card-shadow);
}
.book-card:hover {
  transform: translateY(-4px);
  box-shadow: var(--shadow-lg);
  border-color: var(--accent);
}

.book-cover {
  width: 100%;
  aspect-ratio: 3/4;
  background: var(--bg-elevated);
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

.book-cover img {
  width: 100%;
  height: 100%;
  object-fit: cover;
}

.book-cover .placeholder-icon {
  color: var(--text-muted);
  opacity: .4;
}

.book-info {
  padding: 12px 14px 14px;
}

.book-title {
  font-size: .8rem;
  font-weight: 600;
  color: var(--text-primary);
  display: -webkit-box;
  -webkit-line-clamp: 2;
  -webkit-box-orient: vertical;
  overflow: hidden;
  line-height: 1.4;
  margin-bottom: 8px;
}

.book-progress-bar {
  width: 100%;
  height: 3px;
  background: var(--progress-bg);
  border-radius: 2px;
  overflow: hidden;
  margin-bottom: 4px;
}

.book-progress-fill {
  height: 100%;
  background: var(--progress-fill);
  border-radius: 2px;
  transition: width var(--transition-normal);
}

.book-progress-text {
  font-size: .7rem;
  color: var(--text-muted);
  font-weight: 500;
}

/* Delete button on card */
.book-delete {
  position: absolute;
  top: 8px; right: 8px;
  width: 28px; height: 28px;
  border-radius: var(--radius-full);
  background: rgba(0,0,0,.6);
  color: #FFF;
  border: none;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition-fast);
  z-index: 2;
}
.book-card:hover .book-delete { opacity: 1; }
.book-delete:hover { background: #EF4444; }
.book-delete svg { width: 14px; height: 14px; }

/* Empty State */
.empty-state {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: 80px 20px;
  text-align: center;
}

.empty-state .empty-icon {
  width: 80px; height: 80px;
  color: var(--text-muted);
  opacity: .3;
  margin-bottom: 24px;
  animation: float 3s ease-in-out infinite;
}

@keyframes float {
  0%, 100% { transform: translateY(0); }
  50% { transform: translateY(-10px); }
}

.empty-state h3 {
  font-size: 1.25rem;
  font-weight: 600;
  color: var(--text-secondary);
  margin-bottom: 8px;
}

.empty-state p {
  color: var(--text-muted);
  font-size: .9rem;
  margin-bottom: 24px;
}

/* ==================== READER VIEW ==================== */
#reader-view {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--bg-primary);
  z-index: 50;
  flex-direction: column;
}

#reader-view.active {
  display: flex;
}

/* Reader Header */
.reader-header {
  height: 52px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--glass-border);
  flex-shrink: 0;
  z-index: var(--z-header);
  transition: transform 250ms ease, opacity 250ms ease;
}

.reader-title {
  font-size: .85rem;
  font-weight: 600;
  color: var(--text-primary);
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  max-width: 50vw;
}

.reader-page-info {
  font-size: .8rem;
  color: var(--text-secondary);
  font-weight: 500;
}

/* Canvas Area */
.reader-canvas-area {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  touch-action: pan-y;
}

.page-container {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.page-container canvas {
  max-width: 100%;
  max-height: 100%;
  filter: var(--canvas-filter);
  transition: filter var(--transition-normal);
}

/* Navigation Buttons */
.nav-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 44px; height: 80px;
  background: var(--glass-bg);
  backdrop-filter: blur(10px);
  border: 1px solid var(--glass-border);
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  opacity: 0;
  transition: opacity var(--transition-fast), background var(--transition-fast);
  z-index: 10;
}
.reader-canvas-area:hover .nav-btn { opacity: 1; }
.nav-btn:hover { background: var(--accent-soft); color: var(--accent); }
.nav-btn.prev { left: 12px; }
.nav-btn.next { right: 12px; }
.nav-btn svg { width: 20px; height: 20px; }

/* Reader Footer / Page Info */
.reader-footer {
  height: 44px;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 0 16px;
  background: var(--glass-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-top: 1px solid var(--glass-border);
  flex-shrink: 0;
  transition: transform 250ms ease, opacity 250ms ease;
}

.reader-page-info {
  font-size: .8rem;
  color: var(--text-primary);
  font-weight: 500;
}

.reader-footer-dot {
  font-size: .8rem;
  color: var(--text-muted);
}

.reader-progress-text {
  font-size: .8rem;
  color: var(--text-secondary);
  font-weight: 500;
  white-space: nowrap;
}

.reader-time-remaining {
  font-size: .75rem;
  color: var(--text-muted);
  white-space: nowrap;
}

/* ==================== TOC SIDEBAR ==================== */
.toc-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  z-index: var(--z-sidebar);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-normal), visibility var(--transition-normal);
}
.toc-overlay.active { opacity: 1; visibility: visible; }

.toc-panel {
  position: fixed;
  top: 0; left: 0; bottom: 0;
  width: 320px;
  max-width: 85vw;
  background: var(--bg-elevated);
  border-right: 1px solid var(--border);
  z-index: calc(var(--z-sidebar) + 1);
  transform: translateX(-100%);
  transition: transform var(--transition-normal);
  display: flex;
  flex-direction: column;
}
.toc-panel.active { transform: translateX(0); }

.toc-header {
  height: 56px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
}

.toc-header h3 {
  font-size: 1rem;
  font-weight: 600;
}

.toc-list {
  flex: 1;
  overflow-y: auto;
  padding: 8px 0;
  list-style: none;
}

.toc-list li {
  list-style: none;
}

.toc-item {
  display: block;
  padding: 10px 16px;
  font-size: .85rem;
  color: var(--text-secondary);
  text-decoration: none;
  cursor: pointer;
  border: none;
  background: none;
  width: 100%;
  text-align: left;
  font-family: var(--font-family);
  transition: all var(--transition-fast);
}
.toc-item:hover { background: var(--accent-soft); color: var(--accent); }

.toc-item.depth-1 { padding-left: 32px; font-size: .8rem; }
.toc-item.depth-2 { padding-left: 48px; font-size: .78rem; }

.toc-empty {
  padding: 40px 16px;
  text-align: center;
  color: var(--text-muted);
  font-size: .85rem;
}

/* ==================== SETTINGS PANEL ==================== */
.settings-overlay {
  position: fixed;
  inset: 0;
  background: rgba(0,0,0,.5);
  z-index: var(--z-modal);
  opacity: 0;
  visibility: hidden;
  transition: opacity var(--transition-normal), visibility var(--transition-normal);
}
.settings-overlay.active { opacity: 1; visibility: visible; }

.settings-panel {
  position: fixed;
  top: 50%; left: 50%;
  transform: translate(-50%, -50%) scale(.95);
  width: 420px;
  max-width: 92vw;
  max-height: 85vh;
  background: var(--bg-elevated);
  border: 1px solid var(--border);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-lg);
  z-index: calc(var(--z-modal) + 1);
  opacity: 0;
  visibility: hidden;
  transition: all var(--transition-normal);
  overflow-y: auto;
}
.settings-panel.active { opacity: 1; visibility: visible; transform: translate(-50%, -50%) scale(1); }

.settings-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 20px 24px 16px;
  border-bottom: 1px solid var(--border);
}

.settings-header h3 { font-size: 1.1rem; font-weight: 600; }

.settings-group {
  padding: 16px 24px;
  border-bottom: 1px solid var(--border-subtle);
}

.settings-group:last-child { border-bottom: none; }

.settings-group-title {
  font-size: .7rem;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: .08em;
  margin-bottom: 12px;
}

.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 0;
}

.setting-label {
  font-size: .875rem;
  color: var(--text-primary);
}

/* Toggle Switch */
.toggle {
  position: relative;
  width: 44px; height: 24px;
  background: var(--progress-bg);
  border-radius: 12px;
  cursor: pointer;
  transition: background var(--transition-fast);
  border: none;
}
.toggle.active { background: var(--accent); }
.toggle::after {
  content: '';
  position: absolute;
  top: 2px; left: 2px;
  width: 20px; height: 20px;
  background: #FFF;
  border-radius: 50%;
  transition: transform var(--transition-fast);
  box-shadow: 0 1px 3px rgba(0,0,0,.2);
}
.toggle.active::after { transform: translateX(20px); }

/* Radio Option Buttons */
.radio-group {
  display: flex;
  gap: 8px;
}

.radio-option {
  flex: 1;
  padding: 8px 12px;
  border: 1px solid var(--border);
  border-radius: var(--radius-sm);
  background: var(--bg-surface);
  color: var(--text-secondary);
  font-family: var(--font-family);
  font-size: .8rem;
  font-weight: 500;
  cursor: pointer;
  text-align: center;
  transition: all var(--transition-fast);
}
.radio-option:hover { border-color: var(--accent); color: var(--accent); }
.radio-option.active {
  background: var(--accent-soft);
  border-color: var(--accent);
  color: var(--accent);
  font-weight: 600;
}

/* ==================== TRANSITIONS ==================== */
.page-transition-slide-out-left {
  animation: slideOutLeft var(--transition-normal) forwards;
}
.page-transition-slide-in-right {
  animation: slideInRight var(--transition-normal) forwards;
}
.page-transition-slide-out-right {
  animation: slideOutRight var(--transition-normal) forwards;
}
.page-transition-slide-in-left {
  animation: slideInLeft var(--transition-normal) forwards;
}

@keyframes slideOutLeft {
  from { transform: translateX(0); opacity: 1; }
  to { transform: translateX(-30%); opacity: 0; }
}
@keyframes slideInRight {
  from { transform: translateX(30%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}
@keyframes slideOutRight {
  from { transform: translateX(0); opacity: 1; }
  to { transform: translateX(30%); opacity: 0; }
}
@keyframes slideInLeft {
  from { transform: translateX(-30%); opacity: 0; }
  to { transform: translateX(0); opacity: 1; }
}

.page-transition-fade-out {
  animation: fadeOut 250ms forwards;
}
.page-transition-fade-in {
  animation: fadeIn 250ms forwards;
}
@keyframes fadeOut {
  from { opacity: 1; }
  to { opacity: 0; }
}
@keyframes fadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

/* ==================== FILE INPUT HIDDEN ==================== */
#file-input { display: none; }

/* ==================== LOADING SPINNER ==================== */
.spinner {
  width: 32px; height: 32px;
  border: 3px solid var(--border);
  border-top-color: var(--accent);
  border-radius: 50%;
  animation: spin .6s linear infinite;
}

@keyframes spin { to { transform: rotate(360deg); } }

.loading-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--bg-primary);
  z-index: 5;
}

/* ==================== RESPONSIVE ==================== */
@media (max-width: 768px) {
  .book-grid {
    grid-template-columns: repeat(auto-fill, minmax(140px, 1fr));
    gap: 16px;
  }
  #library-view { padding: 80px 16px 32px; }
  .library-header { flex-direction: column; align-items: flex-start; gap: 8px; }

  /* No arrows on mobile — swipe to navigate */
  .nav-btn { display: none !important; }
}

/* ==================== SCROLL MODE (any screen size) ==================== */
/* Hide nav arrows in scroll mode */
.reader-canvas-area.scroll-mode .nav-btn { display: none !important; }

.reader-canvas-area.scroll-mode {
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
  align-items: flex-start;
  justify-content: flex-start;
}

.scroll-pages-container {
  width: 100%;
  display: flex;
  flex-direction: column;
  gap: 2px;
}

.scroll-page {
  width: 100%;
  background: var(--bg-surface);
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100px;
}

.scroll-page canvas {
  width: 100%;
  height: auto;
  display: block;
  filter: var(--canvas-filter);
  transition: filter var(--transition-normal);
}

/* ==================== REFLOW MODE ==================== */
.reflow-container {
  width: 100%;
  max-width: 720px;
  margin: 0 auto;
  padding: 24px 20px 60px;
  color: var(--text-primary);
  line-height: 1.75;
  font-family: 'Inter', Georgia, serif;
  word-wrap: break-word;
  overflow-wrap: break-word;
}

.reflow-container p {
  margin-bottom: 1em;
  text-align: justify;
  hyphens: auto;
  -webkit-hyphens: auto;
}

.reflow-page {
  margin-bottom: 8px;
}

.reflow-page-sep {
  text-align: center;
  font-size: .7rem;
  color: var(--text-muted);
  padding: 12px 0 16px;
  letter-spacing: .1em;
  opacity: .5;
}

@media (max-width: 480px) {
  .book-grid {
    grid-template-columns: repeat(2, 1fr);
    gap: 12px;
  }
  .app-header { padding: 0 16px; }
  .settings-panel { width: 100vw; max-width: 100vw; border-radius: var(--radius-md); }
}