:root {
  --bg-primary: #0b0d13;
  --bg-secondary: #141722;
  --bg-surface: rgba(22, 26, 38, 0.85);
  --bg-surface-hover: rgba(35, 41, 60, 0.95);
  --border-color: rgba(255, 255, 255, 0.08);
  --border-active: rgba(99, 102, 241, 0.5);
  --text-primary: #f3f4f6;
  --text-secondary: #9ca3af;
  --text-muted: #6b7280;
  --accent-color: #6366f1;
  --accent-hover: #4f46e5;
  --accent-glow: rgba(99, 102, 241, 0.3);
  --shadow-main: 0 25px 50px -12px rgba(0, 0, 0, 0.7);
  --shadow-glass: 0 10px 35px 0 rgba(0, 0, 0, 0.4);
  --dock-bg: rgba(18, 22, 34, 0.88);
  --dock-border: rgba(255, 255, 255, 0.12);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --radius-full: 9999px;
  --font-sans: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --transition-fast: 0.15s cubic-bezier(0.4, 0, 0.2, 1);
  --transition-normal: 0.25s cubic-bezier(0.4, 0, 0.2, 1);
}

[data-theme="light"] {
  --bg-primary: #eef1f6;
  --bg-secondary: #ffffff;
  --bg-surface: rgba(255, 255, 255, 0.88);
  --bg-surface-hover: rgba(240, 243, 248, 0.95);
  --border-color: rgba(0, 0, 0, 0.08);
  --border-active: rgba(99, 102, 241, 0.6);
  --text-primary: #111827;
  --text-secondary: #4b5563;
  --text-muted: #9ca3af;
  --dock-bg: rgba(255, 255, 255, 0.92);
  --dock-border: rgba(0, 0, 0, 0.1);
  --shadow-main: 0 20px 45px -15px rgba(0, 0, 0, 0.15);
  --shadow-glass: 0 8px 32px 0 rgba(0, 0, 0, 0.08);
}

[data-theme="sepia"] {
  --bg-primary: #f2ebd9;
  --bg-secondary: #ebe2cb;
  --bg-surface: rgba(235, 226, 203, 0.9);
  --bg-surface-hover: rgba(222, 211, 184, 0.95);
  --border-color: rgba(92, 70, 41, 0.12);
  --border-active: #8c6d46;
  --text-primary: #3d2f1f;
  --text-secondary: #6e573d;
  --text-muted: #9c8468;
  --accent-color: #8c5620;
  --accent-hover: #754415;
  --accent-glow: rgba(140, 86, 32, 0.25);
  --dock-bg: rgba(235, 226, 203, 0.94);
  --dock-border: rgba(92, 70, 41, 0.18);
}

[data-theme="midnight"] {
  --bg-primary: #040711;
  --bg-secondary: #0a1020;
  --bg-surface: rgba(13, 20, 38, 0.88);
  --bg-surface-hover: rgba(24, 35, 62, 0.95);
  --border-color: rgba(56, 189, 248, 0.14);
  --border-active: #38bdf8;
  --text-primary: #f8fafc;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --accent-color: #38bdf8;
  --accent-hover: #0ea5e9;
  --accent-glow: rgba(56, 189, 248, 0.3);
  --dock-bg: rgba(10, 16, 32, 0.92);
  --dock-border: rgba(56, 189, 248, 0.22);
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
  -webkit-font-smoothing: antialiased;
}

body {
  font-family: var(--font-sans);
  background-color: var(--bg-primary);
  color: var(--text-primary);
  height: 100vh;
  width: 100vw;
  overflow: hidden;
  display: flex;
  flex-direction: column;
  user-select: none;
}

/* Glassmorphism helpers */
.glass {
  background: var(--bg-surface);
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border: 1px solid var(--border-color);
}

.glass-dock {
  background: var(--dock-bg);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border: 1px solid var(--dock-border);
  box-shadow: var(--shadow-glass);
}

/* Base Icon Button */
.btn-icon {
  background: transparent;
  border: 1px solid transparent;
  color: var(--text-secondary);
  width: 36px;
  height: 36px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
}

.btn-icon:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
  border-color: var(--border-color);
}

.btn-icon:active {
  transform: scale(0.95);
}

.btn-icon.active {
  background: var(--accent-glow);
  color: var(--accent-color);
  border-color: var(--border-active);
}

/* Fullscreen App Main Layout (Zero Header) */
.app-body {
  flex: 1;
  width: 100vw;
  height: 100vh;
  display: flex;
  position: relative;
  overflow: hidden;
}

/* Sidebar Drawer */
.sidebar-drawer {
  width: 310px;
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  z-index: 50;
  transform: translateX(-100%);
  transition: transform var(--transition-normal);
  box-shadow: 15px 0 35px rgba(0, 0, 0, 0.4);
}

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

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

.sidebar-tabs {
  display: flex;
  gap: 6px;
}

.sidebar-tab-btn {
  background: transparent;
  border: none;
  color: var(--text-secondary);
  font-size: 0.85rem;
  font-weight: 600;
  padding: 5px 12px;
  border-radius: var(--radius-sm);
  cursor: pointer;
  transition: var(--transition-fast);
}

.sidebar-tab-btn.active {
  color: var(--accent-color);
  background: var(--accent-glow);
}

.sidebar-content {
  flex: 1;
  overflow-y: auto;
  padding: 16px;
  display: flex;
  flex-direction: column;
  gap: 12px;
}

/* Thumbnail Grid */
.thumbnail-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: 12px;
}

.thumb-card {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 6px;
  cursor: pointer;
  padding: 6px;
  border-radius: var(--radius-sm);
  border: 2px solid transparent;
  background: rgba(255, 255, 255, 0.02);
  transition: all var(--transition-fast);
}

.thumb-card:hover {
  background: var(--bg-surface-hover);
  border-color: var(--border-color);
}

.thumb-card.active {
  border-color: var(--accent-color);
  background: var(--accent-glow);
}

.thumb-canvas-container {
  width: 100%;
  aspect-ratio: 1 / 1.414;
  background: #fff;
  border-radius: 4px;
  overflow: hidden;
  box-shadow: 0 4px 10px rgba(0, 0, 0, 0.2);
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
}

.thumb-canvas {
  width: 100%;
  height: 100%;
  object-fit: contain;
}

.thumb-num {
  font-size: 0.75rem;
  font-weight: 600;
  color: var(--text-secondary);
}

/* Outline / TOC List */
.outline-list {
  display: flex;
  flex-direction: column;
  gap: 4px;
  font-size: 0.85rem;
}

.outline-item {
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition-fast);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

.outline-item:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}

/* Main Viewport Stage */
.viewport-stage {
  flex: 1;
  height: 100%;
  width: 100%;
  position: relative;
  overflow: hidden;
  background: var(--bg-primary);
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Zen Presentation Slide Container */
.presentation-container {
  width: 100%;
  height: 100%;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 24px;
  transition: all var(--transition-normal);
}

.presentation-card {
  box-shadow: var(--shadow-main);
  border-radius: 8px;
  background: #fff;
  max-width: 95vw;
  max-height: 94vh;
  display: flex;
  align-items: center;
  justify-content: center;
  position: relative;
  overflow: hidden;
  transition: transform 0.2s cubic-bezier(0.2, 0, 0, 1), opacity 0.2s ease;
}

.presentation-card canvas {
  max-width: 95vw;
  max-height: 92vh;
  object-fit: contain;
  display: block;
}

/* Floating Luxury Dock Controls */
.floating-dock {
  position: absolute;
  bottom: 24px;
  left: 50%;
  transform: translateX(-50%);
  border-radius: var(--radius-full);
  padding: 6px 16px;
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 45;
  transition: opacity 0.3s ease, transform 0.3s ease;
}

.floating-dock:hover {
  opacity: 1 !important;
  transform: translateX(-50%) translateY(0) !important;
}

.dock-separator {
  width: 1px;
  height: 20px;
  background: var(--border-color);
}

.page-navigator {
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: 0.85rem;
  color: var(--text-secondary);
}

.page-input {
  width: 44px;
  text-align: center;
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-weight: 600;
  font-size: 0.85rem;
  padding: 4px 2px;
  outline: none;
  transition: var(--transition-fast);
}

.page-input:focus {
  border-color: var(--accent-color);
  background: rgba(255, 255, 255, 0.15);
}

.zoom-indicator {
  font-size: 0.82rem;
  font-weight: 600;
  color: var(--text-secondary);
  min-width: 38px;
  text-align: center;
  cursor: pointer;
  padding: 4px 6px;
  border-radius: var(--radius-sm);
}

.zoom-indicator:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}

/* Page Navigation Overlay Buttons */
.page-nav-overlay-btn {
  position: absolute;
  top: 50%;
  transform: translateY(-50%);
  width: 52px;
  height: 52px;
  border-radius: 50%;
  background: var(--dock-bg);
  border: 1px solid var(--dock-border);
  box-shadow: var(--shadow-glass);
  color: var(--text-primary);
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  z-index: 35;
  opacity: 0.35;
  transition: all var(--transition-fast);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
}

.viewport-stage:hover .page-nav-overlay-btn {
  opacity: 0.85;
}

.page-nav-overlay-btn:hover {
  opacity: 1 !important;
  background: var(--accent-color);
  color: #fff;
  transform: translateY(-50%) scale(1.1);
  box-shadow: 0 0 20px var(--accent-glow);
}

.page-nav-overlay-btn.prev {
  left: 24px;
}

.page-nav-overlay-btn.next {
  right: 24px;
}

/* ==========================================================================
   High-Tech Downloading & Presentation Loading Screen
   ========================================================================== */
.loader-overlay {
  position: fixed;
  inset: 0;
  background: radial-gradient(circle at center, #14182a 0%, #07090e 100%);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  gap: 24px;
  z-index: 9999;
  opacity: 0;
  pointer-events: none;
  transition: opacity 0.4s ease, transform 0.4s ease;
}

.loader-overlay.active {
  opacity: 1;
  pointer-events: auto;
}

.loader-visual-box {
  position: relative;
  width: 110px;
  height: 110px;
  display: flex;
  align-items: center;
  justify-content: center;
}

.spinner-ring-outer {
  position: absolute;
  inset: 0;
  border-radius: 50%;
  border: 3px solid transparent;
  border-top-color: #6366f1;
  border-right-color: #ec4899;
  animation: spin 1.2s cubic-bezier(0.5, 0, 0.5, 1) infinite;
  box-shadow: 0 0 30px rgba(99, 102, 241, 0.4);
}

.spinner-ring-inner {
  position: absolute;
  inset: 12px;
  border-radius: 50%;
  border: 2.5px solid transparent;
  border-bottom-color: #38bdf8;
  border-left-color: #a855f7;
  animation: spin-reverse 0.9s linear infinite;
}

.loader-icon-center {
  font-size: 28px;
  color: #ffffff;
  background: linear-gradient(135deg, #6366f1, #ec4899);
  width: 56px;
  height: 56px;
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 6px 24px rgba(99, 102, 241, 0.45);
  animation: pulse-icon 2s ease-in-out infinite;
}

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

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

@keyframes pulse-icon {
  0%, 100% { transform: scale(1); filter: brightness(1); }
  50% { transform: scale(1.08); filter: brightness(1.25); }
}

.loader-info {
  text-align: center;
  display: flex;
  flex-direction: column;
  gap: 6px;
}

.loader-text {
  font-size: 1.25rem;
  font-weight: 700;
  letter-spacing: -0.01em;
  color: #ffffff;
}

.loader-subtext {
  font-size: 0.88rem;
  color: var(--text-secondary);
}

.progress-section {
  width: 320px;
  max-width: 85vw;
  display: flex;
  flex-direction: column;
  gap: 8px;
}

.progress-bar-container {
  width: 100%;
  height: 8px;
  background: rgba(255, 255, 255, 0.08);
  border-radius: 9999px;
  overflow: hidden;
  border: 1px solid rgba(255, 255, 255, 0.05);
  box-shadow: inset 0 1px 3px rgba(0, 0, 0, 0.5);
}

.progress-bar-fill {
  height: 100%;
  width: 0%;
  background: linear-gradient(90deg, #6366f1, #a855f7, #ec4899);
  border-radius: 9999px;
  transition: width 0.25s ease-out;
  box-shadow: 0 0 12px rgba(99, 102, 241, 0.7);
}

.progress-meta {
  display: flex;
  justify-content: space-between;
  align-items: center;
  font-size: 0.78rem;
  font-weight: 600;
  color: var(--text-muted);
}

#loaderPercent {
  color: #f3f4f6;
  font-weight: 700;
}

/* Theme selector dropdown (Near bottom dock) */
.theme-menu {
  position: absolute;
  bottom: 84px;
  left: 50%;
  transform: translateX(-50%) translateY(10px);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-glass);
  padding: 6px;
  display: flex;
  flex-direction: column;
  gap: 4px;
  z-index: 60;
  opacity: 0;
  pointer-events: none;
  transition: all var(--transition-fast);
}

.theme-menu.open {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}

.theme-option {
  display: flex;
  align-items: center;
  gap: 8px;
  padding: 8px 14px;
  font-size: 0.85rem;
  border-radius: var(--radius-sm);
  color: var(--text-secondary);
  cursor: pointer;
  transition: var(--transition-fast);
}

.theme-option:hover {
  background: var(--bg-surface-hover);
  color: var(--text-primary);
}

.theme-option.active {
  color: var(--accent-color);
  font-weight: 600;
}

.theme-dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  border: 1px solid var(--border-color);
}

/* Search Box Container */
.search-box-container {
  position: absolute;
  top: 24px;
  left: 50%;
  transform: translateX(-50%) translateY(-10px);
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-glass);
  padding: 8px 14px;
  display: flex;
  align-items: center;
  gap: 10px;
  z-index: 55;
  opacity: 0;
  pointer-events: none;
  transition: all var(--transition-fast);
}

.search-box-container.open {
  opacity: 1;
  transform: translateX(-50%) translateY(0);
  pointer-events: auto;
}

.search-input {
  background: rgba(255, 255, 255, 0.08);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  color: var(--text-primary);
  font-size: 0.85rem;
  padding: 6px 12px;
  outline: none;
  width: 220px;
}

.search-match-count {
  font-size: 0.75rem;
  color: var(--text-muted);
}

/* Toast Notifications */
.toast-container {
  position: fixed;
  top: 24px;
  right: 24px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 110;
  pointer-events: none;
}

.toast {
  background: var(--bg-surface);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-glass);
  backdrop-filter: blur(16px);
  padding: 10px 16px;
  border-radius: var(--radius-md);
  font-size: 0.85rem;
  color: var(--text-primary);
  display: flex;
  align-items: center;
  gap: 10px;
  transform: translateX(100%);
  opacity: 0;
  transition: all var(--transition-normal);
}

.toast.show {
  transform: translateX(0);
  opacity: 1;
}

/* Tooltip helper */
[data-tooltip] {
  position: relative;
}

[data-tooltip]::after {
  content: attr(data-tooltip);
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%) scale(0.95);
  background: rgba(0, 0, 0, 0.88);
  color: #fff;
  font-size: 0.72rem;
  padding: 4px 8px;
  border-radius: 4px;
  white-space: nowrap;
  pointer-events: none;
  opacity: 0;
  transition: all var(--transition-fast);
  z-index: 100;
}

[data-tooltip]:hover::after {
  opacity: 1;
  transform: translateX(-50%) scale(1);
}

/* Responsive Rules */
@media (max-width: 768px) {
  .floating-dock {
    width: 95%;
    bottom: 12px;
    padding: 4px 8px;
    gap: 6px;
    justify-content: space-between;
  }
  .dock-separator {
    display: none;
  }
  .sidebar-drawer {
    width: 270px;
  }
  .page-nav-overlay-btn {
    display: none;
  }
  .presentation-container {
    padding: 8px;
  }
}