/* Fluent Design System CSS - Matching Dart Intensive Listening App */

:root {
  --font-family: 'SourceHanSansSC', 'Segoe UI', -apple-system, BlinkMacSystemFont, 'PingFang SC', 'Microsoft YaHei', sans-serif;
  
  /* Fluent Red Accent */
  --accent: #d13438;
  --accent-hover: #c42b1c;
  --accent-pressed: #a80000;
  --accent-tint: rgba(209, 52, 56, 0.08);
  --accent-tint-hover: rgba(209, 52, 56, 0.14);
  --accent-light: rgba(209, 52, 56, 0.12);
  --accent-text: #ffffff;

  /* WinUI 3 Motion Tokens */
  --ease-standard: cubic-bezier(0.8, 0, 0.2, 1);
  --ease-decel: cubic-bezier(0.1, 0.9, 0.2, 1);
  --ease-accel: cubic-bezier(0.7, 0, 1, 0.5);
  --ease-spring: cubic-bezier(0.34, 1.56, 0.64, 1);
  
  --trans-micro: 90ms ease-out;
  --trans-fast: 160ms var(--ease-decel);
  --trans-normal: 240ms var(--ease-decel);
  --trans-slow: 340ms var(--ease-decel);
  --trans-spring: 320ms var(--ease-spring);

  /* Light Theme */
  --bg-app: #f3f3f3;
  --bg-mica: radial-gradient(1200px circle at 50% 0px, rgba(255, 255, 255, 0.82) 0%, rgba(243, 243, 243, 0.96) 100%), #f3f3f3;
  --bg-card: #ffffff;
  --bg-card-header: #f8f9fa;
  --bg-surface: #ffffff;
  --bg-input: #ffffff;
  --bg-btn: #fbfcfd;
  --bg-btn-hover: #f5f5f5;
  --bg-btn-pressed: #ebebeb;
  
  --border-card: rgba(0, 0, 0, 0.08);
  --border-btn: rgba(0, 0, 0, 0.16);
  --border-btn-bottom: rgba(0, 0, 0, 0.24);
  --border-divider: rgba(0, 0, 0, 0.08);
  
  --text-primary: rgba(0, 0, 0, 0.89);
  --text-secondary: rgba(0, 0, 0, 0.60);
  --text-caption: rgba(0, 0, 0, 0.45);
  --text-disabled: rgba(0, 0, 0, 0.28);
  
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.04), 0 0 1px rgba(0, 0, 0, 0.07);
  --shadow-hover: 0 4px 14px rgba(0, 0, 0, 0.08), 0 0 1px rgba(0, 0, 0, 0.08);
  --shadow-flyout: 0 12px 28px rgba(0, 0, 0, 0.16), 0 2px 8px rgba(0, 0, 0, 0.08);
  --shadow-dialog: 0 24px 48px rgba(0, 0, 0, 0.24), 0 4px 16px rgba(0, 0, 0, 0.12);

  --radius-sm: 4px;
  --radius-md: 6px;
  --radius-lg: 8px;
  --radius-pill: 9999px;
}

[data-theme="dark"] {
  --accent: #e81123;
  --accent-hover: #f12d3e;
  --accent-pressed: #c42b1c;
  --accent-tint: rgba(232, 17, 35, 0.14);
  --accent-tint-hover: rgba(232, 17, 35, 0.22);
  --accent-light: rgba(232, 17, 35, 0.18);
  --accent-text: #ffffff;

  --bg-app: #202020;
  --bg-mica: radial-gradient(1200px circle at 50% 0px, rgba(46, 46, 46, 0.72) 0%, rgba(32, 32, 32, 0.98) 100%), #202020;
  --bg-card: #2c2c2c;
  --bg-card-header: #262626;
  --bg-surface: #2d2d2d;
  --bg-input: #1f1f1f;
  --bg-btn: #2d2d2d;
  --bg-btn-hover: #383838;
  --bg-btn-pressed: #242424;
  
  --border-card: rgba(255, 255, 255, 0.08);
  --border-btn: rgba(255, 255, 255, 0.16);
  --border-btn-bottom: rgba(255, 255, 255, 0.24);
  --border-divider: rgba(255, 255, 255, 0.08);
  
  --text-primary: rgba(255, 255, 255, 0.95);
  --text-secondary: rgba(255, 255, 255, 0.70);
  --text-caption: rgba(255, 255, 255, 0.48);
  --text-disabled: rgba(255, 255, 255, 0.25);
  
  --shadow-card: 0 1px 3px rgba(0, 0, 0, 0.3), 0 0 1px rgba(255, 255, 255, 0.08);
  --shadow-hover: 0 6px 18px rgba(0, 0, 0, 0.45), 0 0 1px rgba(255, 255, 255, 0.12);
  --shadow-flyout: 0 16px 36px rgba(0, 0, 0, 0.55), 0 2px 8px rgba(0, 0, 0, 0.4);
  --shadow-dialog: 0 28px 56px rgba(0, 0, 0, 0.7), 0 4px 18px rgba(0, 0, 0, 0.5);
}

/* Reset and Global Styles */
* {
  box-sizing: border-box;
  margin: 0;
  padding: 0;
  -webkit-tap-highlight-color: transparent;
}

body {
  font-family: var(--font-family);
  background: var(--bg-mica);
  color: var(--text-primary);
  line-height: 1.4;
  overflow: hidden;
  height: 100vh;
  width: 100vw;
  user-select: none;
}

/* Windows 11 Modern Scrollbars */
::-webkit-scrollbar {
  width: 8px;
  height: 8px;
}
::-webkit-scrollbar-track {
  background: transparent;
}
::-webkit-scrollbar-thumb {
  background: rgba(0, 0, 0, 0.15);
  border-radius: 4px;
  border: 2px solid transparent;
  background-clip: padding-box;
  transition: background-color var(--trans-fast);
}
::-webkit-scrollbar-thumb:hover {
  background: rgba(0, 0, 0, 0.32);
  border: 1px solid transparent;
  background-clip: padding-box;
}
[data-theme="dark"] ::-webkit-scrollbar-thumb {
  background: rgba(255, 255, 255, 0.18);
}
[data-theme="dark"] ::-webkit-scrollbar-thumb:hover {
  background: rgba(255, 255, 255, 0.36);
}

/* Tabular figures for time/numbers */
.tabular-nums {
  font-variant-numeric: tabular-nums;
  font-feature-settings: "tnum";
}

/* App Shell Layout */
#app {
  display: flex;
  flex-direction: column;
  height: 100vh;
  width: 100vw;
  overflow: hidden;
  background: var(--bg-mica);
}

/* Header */
.app-header {
  height: 48px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0 16px;
  background: transparent;
  backdrop-filter: blur(16px);
  -webkit-backdrop-filter: blur(16px);
  border-bottom: 1px solid var(--border-divider);
  flex-shrink: 0;
  z-index: 100;
}

.header-left {
  display: flex;
  align-items: center;
  gap: 10px;
  min-width: 0;
  flex: 1;
  overflow: hidden;
}

.header-right {
  display: flex;
  align-items: center;
  gap: 8px;
  flex-shrink: 0;
}

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

/* In player view, import actions are hidden to keep header clean and give focus to current lesson */
#app[data-view="player"] .header-import-actions {
  display: none !important;
}

.icon-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border-radius: var(--radius-sm);
  background: transparent;
  border: none;
  color: var(--text-primary);
  cursor: pointer;
  transition: background-color var(--trans-fast), transform var(--trans-micro);
}

.icon-btn:hover {
  background-color: var(--bg-btn-hover);
}

.icon-btn:active {
  background-color: var(--bg-btn-pressed);
  transform: scale(0.92);
}

.app-logo-mark {
  width: 22px;
  height: 22px;
  border-radius: 5px;
  flex-shrink: 0;
  display: inline-block;
  vertical-align: middle;
  box-shadow: 0 1px 4px rgba(184, 15, 40, 0.25);
}

.app-title {
  font-size: 16px;
  font-weight: 600;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  flex: 1;
  min-width: 0;
}

/* Version & Commit Badge */
.app-version-badge {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  padding: 3px 8px;
  background: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: 12px;
  font-family: ui-monospace, SFMono-Regular, "Cascadia Code", "Segoe UI Mono", Menlo, Consolas, monospace;
  font-size: 11px;
  font-weight: 500;
  color: var(--text-secondary);
  text-decoration: none;
  cursor: pointer;
  line-height: 1.2;
  transition: all var(--trans-fast);
}

.app-version-badge:hover {
  background: var(--bg-subtle-hover);
  color: var(--accent);
  border-color: var(--accent);
}

.app-version-badge .commit-text {
  font-size: 10px;
  opacity: 0.85;
  background: rgba(128, 128, 128, 0.12);
  padding: 1px 5px;
  border-radius: 4px;
}

/* Fluent Buttons */
.fluent-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 6px 14px;
  font-size: 14px;
  font-family: inherit;
  font-weight: 400;
  border-radius: var(--radius-sm);
  background-color: var(--bg-btn);
  border: 1px solid var(--border-btn);
  border-bottom-color: var(--border-btn-bottom);
  color: var(--text-primary);
  cursor: pointer;
  transition: all var(--trans-fast), transform var(--trans-micro);
  white-space: nowrap;
  outline: none;
  box-sizing: border-box;
}

.fluent-btn:hover {
  background-color: var(--bg-btn-hover);
  box-shadow: var(--shadow-card);
  transform: translateY(-0.5px);
}

.fluent-btn:active {
  background-color: var(--bg-btn-pressed);
  transform: scale(0.97);
}

.fluent-btn:focus-visible {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

.fluent-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
  transform: none;
  box-shadow: none;
}

.fluent-btn.filled {
  background: linear-gradient(180deg, rgba(255, 255, 255, 0.12) 0%, rgba(0, 0, 0, 0.05) 100%), var(--accent);
  border-color: var(--accent);
  color: var(--accent-text);
  font-weight: 500;
  box-shadow: 0 1px 3px rgba(209, 52, 56, 0.25);
}

.fluent-btn.filled:hover {
  filter: brightness(1.08);
  box-shadow: 0 2px 8px rgba(209, 52, 56, 0.4);
  transform: translateY(-0.5px);
}

.fluent-btn.filled:active {
  filter: brightness(0.92);
  transform: scale(0.97);
}

.fluent-btn.play-btn {
  width: 44px;
  height: 44px;
  min-width: 44px;
  border-radius: 50%;
  padding: 0;
  display: inline-flex;
  align-items: center;
  justify-content: center;
  box-shadow: 0 4px 14px rgba(209, 52, 56, 0.35);
  transition: transform var(--trans-spring), box-shadow var(--trans-fast), filter var(--trans-fast);
}

.fluent-btn.play-btn:hover {
  transform: scale(1.08);
  box-shadow: 0 6px 20px rgba(209, 52, 56, 0.48);
}

.fluent-btn.play-btn:active {
  transform: scale(0.93);
}

.fluent-btn.play-btn #play-icon {
  margin-left: 2px; /* optical centering for triangle */
}

.fluent-btn.sm {
  padding: 3px 8px;
  font-size: 13px;
}

/* Main Workspace */
.main-workspace {
  flex: 1;
  display: flex;
  overflow: hidden;
  position: relative;
}

/* Home / Empty View */
.home-view {
  flex: 1;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: space-between;
  padding: 32px 24px 20px;
  overflow-y: auto;
  box-sizing: border-box;
}

.home-content {
  width: 100%;
  max-width: 900px;
  display: flex;
  flex-direction: column;
  align-items: center;
  flex: 1;
  min-height: 0;
  justify-content: center;
}

.home-footer {
  width: 100%;
  max-width: 900px;
  margin-top: auto;
  padding: 24px 0 8px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
}

.footer-links {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 13px;
  color: var(--text-secondary);
}

.footer-legal-link {
  color: var(--text-secondary);
  text-decoration: none;
  font-size: 13px;
  cursor: pointer;
  transition: color var(--trans-fast);
}

.footer-legal-link:hover {
  color: var(--accent);
  text-decoration: underline;
}

.footer-sep {
  color: var(--border-divider);
  user-select: none;
}

.empty-state-box {
  display: flex;
  flex-direction: column;
  align-items: center;
  text-align: center;
  max-width: 480px;
  margin: auto;
}

.empty-icon,
.empty-logo-mark {
  width: 64px;
  height: 64px;
  margin-bottom: 20px;
}

.empty-icon {
  color: var(--text-secondary);
}

.empty-logo-mark {
  border-radius: 14px;
  box-shadow: 0 8px 24px rgba(184, 15, 40, 0.28);
  transition: transform var(--trans-spring);
  display: block;
  margin-left: auto;
  margin-right: auto;
}

.empty-logo-mark:hover {
  transform: scale(1.08);
}

.empty-title {
  font-size: 22px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.empty-desc {
  font-size: 14px;
  color: var(--text-secondary);
  margin-bottom: 24px;
  line-height: 1.5;
}

.empty-actions {
  display: flex;
  gap: 12px;
  flex-wrap: wrap;
  justify-content: center;
}

/* Recent Lessons Section */
.recent-section {
  width: 100%;
  max-width: 900px;
  margin-top: 10px;
}

.recent-title {
  font-size: 18px;
  font-weight: 600;
  margin-bottom: 16px;
  color: var(--text-primary);
}

.lesson-list {
  display: flex;
  flex-direction: column;
  gap: 10px;
}

.lesson-row {
  display: flex;
  align-items: center;
  height: 84px;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-md);
  padding: 0 20px;
  box-shadow: var(--shadow-card);
  transition: all var(--trans-fast);
  cursor: pointer;
}

.lesson-row:hover {
  background-color: var(--accent-tint);
  border-color: rgba(209, 52, 56, 0.3);
  box-shadow: var(--shadow-hover);
  transform: translateY(-1px);
}

.lesson-row-info {
  flex: 1;
  min-width: 0;
  margin-right: 16px;
}

.lesson-row-title {
  font-size: 16px;
  font-weight: 500;
  color: var(--text-primary);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
  margin-bottom: 6px;
}

.lesson-row-meta {
  display: flex;
  align-items: center;
  gap: 16px;
  font-size: 12px;
  color: var(--text-secondary);
}

.progress-track {
  width: 140px;
  height: 4px;
  background-color: rgba(0, 0, 0, 0.08);
  border-radius: 2px;
  overflow: hidden;
  position: relative;
}

[data-theme="dark"] .progress-track {
  background-color: rgba(255, 255, 255, 0.12);
}

.progress-fill {
  height: 100%;
  background-color: var(--accent);
  border-radius: 2px;
}

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

/* Playback View Layout */
.player-view {
  flex: 1;
  display: flex;
  width: 100%;
  height: 100%;
  overflow: hidden;
}

/* Left / Top: Player Section */
.player-section {
  flex: 100;
  display: flex;
  flex-direction: column;
  padding: 16px 20px;
  overflow: hidden;
  border-right: 1px solid var(--border-divider);
  background: transparent;
  height: 100%;
  box-sizing: border-box;
}

/* Right / Bottom: Transcript Section */
.transcript-section {
  flex: 168;
  display: flex;
  flex-direction: column;
  padding: 16px 20px 20px;
  overflow-y: auto;
  background: transparent;
  position: relative;
  height: 100%;
  box-sizing: border-box;
}

/* Question Area */
.question-container {
  flex: 1 1 0;
  min-height: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  margin-bottom: 12px;
  overflow: hidden;
}

.fluent-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-top-color: rgba(255, 255, 255, 0.45);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  padding: 18px 20px;
  overflow-y: auto;
  max-height: 100%;
  box-sizing: border-box;
  transition: box-shadow var(--trans-fast), border-color var(--trans-fast);
}

[data-theme="dark"] .fluent-card {
  border-top-color: rgba(255, 255, 255, 0.12);
}

.question-title {
  font-size: 18px;
  font-weight: 600;
  line-height: 1.4;
  margin-bottom: 14px;
  color: var(--text-primary);
}

.question-options {
  display: flex;
  flex-direction: column;
  gap: 8px;
  margin-bottom: 16px;
}

.option-item {
  display: flex;
  align-items: center;
  padding: 10px 14px;
  border-radius: var(--radius-sm);
  background-color: transparent;
  border: 1px solid transparent;
  cursor: pointer;
  transition: background-color var(--trans-fast), border-color var(--trans-fast), transform var(--trans-fast);
  color: var(--text-primary);
  font-size: 14px;
}

.option-item:hover {
  background-color: var(--accent-tint);
  transform: translateX(3px);
}

.option-item.selected {
  background-color: var(--accent-tint-hover);
  border-color: var(--accent);
  font-weight: 500;
  transform: translateX(3px);
}

.option-radio {
  width: 18px;
  height: 18px;
  border-radius: 50%;
  border: 2px solid var(--text-secondary);
  margin-right: 10px;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  transition: border-color var(--trans-fast), transform var(--trans-micro);
}

.option-item:hover .option-radio {
  border-color: var(--accent);
}

.option-item.selected .option-radio {
  border-color: var(--accent);
}

.option-radio-dot {
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background-color: var(--accent);
  opacity: 0;
  transform: scale(0);
  transition: transform 220ms var(--ease-spring), opacity 150ms var(--ease-decel);
}

.option-item.selected .option-radio-dot {
  opacity: 1;
  transform: scale(1);
}

.answer-box {
  margin-top: 10px;
  padding-top: 10px;
  border-top: 1px dashed var(--border-divider);
  display: flex;
  align-items: center;
  gap: 12px;
}

.answer-text {
  font-weight: 600;
  color: var(--accent);
  font-size: 14px;
}

/* Playback Controls Container */
.controls-container {
  display: flex;
  flex-direction: column;
  gap: 10px;
  flex-shrink: 0;
  padding-top: 10px;
  padding-bottom: 4px;
  box-sizing: border-box;
  overflow: visible;
  position: relative;
  z-index: 5;
}

/* Slider */
.slider-wrapper {
  display: flex;
  flex-direction: column;
  gap: 6px;
  width: 100%;
}

.fluent-slider {
  -webkit-appearance: none;
  appearance: none;
  width: 100%;
  height: 4px;
  border-radius: 2px;
  background: linear-gradient(to right, var(--accent) var(--progress, 0%), rgba(0, 0, 0, 0.15) var(--progress, 0%));
  outline: none;
  cursor: pointer;
  transition: height var(--trans-fast);
}

[data-theme="dark"] .fluent-slider {
  background: linear-gradient(to right, var(--accent) var(--progress, 0%), rgba(255, 255, 255, 0.2) var(--progress, 0%));
}

.slider-wrapper:hover .fluent-slider,
.fluent-slider:hover {
  height: 6px;
}

.fluent-slider::-webkit-slider-thumb {
  -webkit-appearance: none;
  appearance: none;
  width: 16px;
  height: 16px;
  border-radius: 50%;
  background-color: var(--accent);
  border: 3px solid #ffffff;
  box-shadow: 0 1px 4px rgba(0, 0, 0, 0.3);
  cursor: pointer;
  transition: transform var(--trans-spring), box-shadow var(--trans-fast), background-color var(--trans-fast);
}

[data-theme="dark"] .fluent-slider::-webkit-slider-thumb {
  border-color: #2c2c2c;
}

.fluent-slider:hover::-webkit-slider-thumb {
  transform: scale(1.24);
  box-shadow: 0 2px 8px rgba(209, 52, 56, 0.45);
}

.fluent-slider:active::-webkit-slider-thumb {
  transform: scale(1.36);
  background-color: var(--accent-hover);
}

.time-row {
  display: flex;
  justify-content: space-between;
  font-size: 12px;
  color: var(--text-secondary);
}

/* Control Buttons Row */
.controls-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  min-height: 52px;
  padding: 6px 0;
  box-sizing: border-box;
  flex-shrink: 0;
  overflow: visible;
}

.controls-row .fluent-btn {
  min-height: 34px;
  padding: 6px 14px;
  font-size: 13.5px;
}

/* Checkboxes and toggles */
.toggles-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 18px;
  margin-top: 4px;
}

.fluent-checkbox {
  display: inline-flex;
  align-items: center;
  gap: 8px;
  font-size: 13px;
  color: var(--text-primary);
  cursor: pointer;
  user-select: none;
}

.checkbox-box {
  width: 16px;
  height: 16px;
  border-radius: 3px;
  border: 1px solid var(--text-secondary);
  display: inline-flex;
  align-items: center;
  justify-content: center;
  background-color: var(--bg-input);
  transition: background-color var(--trans-fast), border-color var(--trans-fast), transform var(--trans-micro);
}

.fluent-checkbox:hover .checkbox-box {
  border-color: var(--accent);
}

.fluent-checkbox:active .checkbox-box {
  transform: scale(0.92);
}

.fluent-checkbox.checked .checkbox-box {
  background-color: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

.fluent-checkbox .check-icon {
  width: 12px;
  height: 12px;
  opacity: 0;
  transform: scale(0);
  transition: transform 200ms var(--ease-spring), opacity 150ms var(--ease-decel);
}

.fluent-checkbox.checked .check-icon {
  opacity: 1;
  transform: scale(1);
}

/* Actions Row (Repeat, Cloze toggles) */
.actions-row {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  flex-wrap: wrap;
  margin-top: 4px;
}

/* Question Index Strip */
.question-strip-container {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-top: 8px;
  overflow: hidden;
}

.question-strip-label {
  font-size: 12px;
  color: var(--text-secondary);
  white-space: nowrap;
}

.question-strip {
  display: flex;
  align-items: center;
  gap: 6px;
  overflow-x: auto;
  padding: 4px 2px;
  scrollbar-width: thin;
}

.question-strip::-webkit-scrollbar {
  height: 4px;
}

.question-strip::-webkit-scrollbar-thumb {
  background: var(--border-divider);
  border-radius: 2px;
}

.strip-item {
  padding: 4px 10px;
  font-size: 12px;
  border-radius: var(--radius-sm);
  background-color: var(--bg-btn);
  border: 1px solid var(--border-btn);
  color: var(--text-primary);
  cursor: pointer;
  white-space: nowrap;
  transition: all var(--trans-fast), transform var(--trans-micro);
}

.strip-item:hover {
  background-color: var(--bg-btn-hover);
  transform: translateY(-1px);
  box-shadow: var(--shadow-card);
}

.strip-item:active {
  transform: scale(0.95);
}

.strip-item.active {
  background-color: var(--accent);
  border-color: var(--accent);
  color: var(--accent-text);
  font-weight: 500;
  box-shadow: 0 2px 8px rgba(209, 52, 56, 0.35);
}

/* Transcript Pane Subtitle Cards */
.transcript-pane {
  display: flex;
  flex-direction: column;
  gap: 12px;
  transition: filter var(--trans-normal);
}

.transcript-pane.masked {
  filter: blur(8px);
}

.transcript-card {
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-top-color: rgba(255, 255, 255, 0.4);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-card);
  overflow: hidden;
  transition: border-color var(--trans-fast), box-shadow var(--trans-fast);
}

[data-theme="dark"] .transcript-card {
  border-top-color: rgba(255, 255, 255, 0.12);
}

.transcript-card.active {
  border-color: rgba(209, 52, 56, 0.3);
  box-shadow: var(--shadow-hover);
}

.transcript-card-header {
  display: flex;
  align-items: center;
  padding: 10px 14px;
  background-color: var(--bg-card-header);
  border-bottom: 1px solid var(--border-divider);
  cursor: pointer;
  user-select: none;
  transition: background-color var(--trans-fast);
}

.transcript-card.active .transcript-card-header {
  background-color: var(--accent-tint);
}

.header-icon {
  margin-right: 8px;
  color: var(--text-secondary);
}

.transcript-card.active .header-icon {
  color: var(--accent);
}

.card-title {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-primary);
  flex: 1;
}

.card-badge {
  font-size: 12px;
  color: var(--text-caption);
}

.cue-list {
  display: flex;
  flex-direction: column;
}

/* WinUI Collapsible Smooth Height Transition */
.cue-list.collapsible {
  overflow: hidden;
  max-height: 2500px;
  opacity: 1;
  transition: max-height 300ms var(--ease-decel), opacity 240ms var(--ease-decel);
}

.cue-list.collapsible.collapsed {
  max-height: 0 !important;
  opacity: 0 !important;
  padding-top: 0 !important;
  padding-bottom: 0 !important;
  pointer-events: none;
}

.cue-row {
  display: flex;
  align-items: flex-start;
  padding: 12px 14px;
  border-bottom: 1px solid var(--border-divider);
  cursor: pointer;
  transition: background-color var(--trans-fast);
  min-height: 52px;
  position: relative;
}

.cue-row:last-child {
  border-bottom: none;
}

.cue-row:hover {
  background-color: var(--bg-btn-hover);
}

.cue-row.active {
  background-color: var(--accent-tint);
}

/* Signature WinUI Selection Pill Indicator */
.cue-row::before {
  content: '';
  position: absolute;
  left: 0;
  top: 50%;
  transform: translateY(-50%) scaleY(0);
  width: 3.5px;
  height: 22px;
  background-color: var(--accent);
  border-radius: 0 3px 3px 0;
  transition: transform 220ms var(--ease-spring), opacity 160ms var(--ease-decel);
  opacity: 0;
}

.cue-row.active::before {
  transform: translateY(-50%) scaleY(1);
  opacity: 1;
}

.cue-time {
  font-size: 12px;
  color: var(--text-secondary);
  width: 48px;
  flex-shrink: 0;
  margin-top: 2px;
}

.cue-text {
  flex: 1;
  font-size: 16px;
  line-height: 1.5;
  color: var(--text-primary);
  word-break: break-word;
}

/* Cloze Words Styling with Spring Reveal Animation */
@keyframes clozeRevealPulse {
  0% { transform: scale(0.94); filter: brightness(1.2); }
  50% { transform: scale(1.05); }
  100% { transform: scale(1); filter: brightness(1); }
}

.cloze-word {
  display: inline-block;
  padding: 1px 5px;
  margin: 1px 2px;
  border-radius: var(--radius-sm);
  transition: filter var(--trans-normal), background-color var(--trans-fast), color var(--trans-fast), transform var(--trans-fast);
  cursor: pointer;
}

.cloze-word.hidden {
  filter: blur(4.5px);
  background-color: var(--accent-light);
  border-bottom: 2px solid var(--accent);
  user-select: none;
}

.cloze-word.hidden:hover {
  filter: blur(3.5px);
  background-color: var(--accent-tint-hover);
  transform: translateY(-1px);
}

.cloze-word.revealed {
  background-color: var(--accent-tint);
  border-bottom: 2px solid transparent;
  animation: clozeRevealPulse 260ms var(--ease-spring);
}

/* Repeated Cues Expander & Unassigned Expander */
.expander-header,
.transcript-card-header.is-expander {
  display: flex;
  align-items: center;
  padding: 8px 14px;
  background-color: var(--bg-card-header);
  cursor: pointer;
  font-size: 13px;
  color: var(--text-secondary);
  transition: background-color var(--trans-fast);
  user-select: none;
}

.expander-header:hover,
.transcript-card-header.is-expander:hover {
  background-color: var(--bg-btn-hover);
  color: var(--text-primary);
}

.expander-header {
  border-top: 1px solid var(--border-divider);
}

.expander-chevron {
  width: 14px;
  height: 14px;
  transition: transform 240ms var(--ease-decel);
  margin-right: 8px;
  flex-shrink: 0;
}

.expander-header.expanded .expander-chevron,
.transcript-card-header.expanded .expander-chevron {
  transform: rotate(90deg);
}

/* Legal Modal & Privacy Styles */
.fluent-dialog.legal-dialog {
  max-width: 660px;
  max-height: 85vh;
}

.legal-nav {
  display: flex;
  border-bottom: 1px solid var(--border-divider);
  padding: 0 24px;
  gap: 16px;
  background-color: var(--bg-card);
}

.legal-tab {
  padding: 10px 4px;
  font-size: 14px;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all var(--trans-fast);
}

.legal-tab:hover {
  color: var(--text-primary);
}

.legal-tab.active {
  color: var(--accent);
  font-weight: 600;
  border-bottom-color: var(--accent);
}

.legal-content {
  padding: 16px 24px;
  font-size: 13px;
  line-height: 1.65;
  color: var(--text-primary);
  max-height: 52vh;
  overflow-y: auto;
  user-select: text;
}

.legal-content h4 {
  font-size: 15px;
  font-weight: 600;
  margin: 14px 0 6px;
  color: var(--text-primary);
}

.legal-content h4:first-child {
  margin-top: 0;
}

.legal-content p {
  margin-bottom: 10px;
  color: var(--text-secondary);
}

.legal-content ul {
  margin: 0 0 10px 20px;
  color: var(--text-secondary);
}

.legal-content li {
  margin-bottom: 4px;
}

/* Fullscreen Blocking Legal Overlay (全屏阻断式协议与隐私弹窗) */
.blocking-legal-overlay {
  position: fixed;
  inset: 0;
  z-index: 99999;
  background: rgba(0, 0, 0, 0.78);
  backdrop-filter: blur(24px);
  -webkit-backdrop-filter: blur(24px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  animation: fadeIn 200ms ease-out;
}

.blocking-legal-modal {
  max-width: 760px;
  width: 100%;
  max-height: 88vh;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-flyout);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  animation: dialogZoomIn 220ms cubic-bezier(0.1, 0.9, 0.2, 1);
}

.blocking-legal-header {
  display: flex;
  align-items: center;
  padding: 20px 24px 16px;
  background-color: var(--bg-card-header);
  border-bottom: 1px solid var(--border-divider);
  gap: 16px;
}

.brand-avatar {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background-color: var(--accent);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(209, 52, 56, 0.35);
}

.brand-heading {
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0 0 4px 0;
}

.brand-subheading {
  font-size: 13px;
  color: var(--text-secondary);
}

.blocking-tabs {
  display: flex;
  border-bottom: 1px solid var(--border-divider);
  background-color: var(--bg-card);
  padding: 0 24px;
  gap: 12px;
}

.blocking-tab-btn {
  padding: 12px 6px;
  font-size: 14px;
  font-weight: 500;
  color: var(--text-secondary);
  background: none;
  border: none;
  border-bottom: 2px solid transparent;
  cursor: pointer;
  transition: all var(--trans-fast);
}

.blocking-tab-btn:hover {
  color: var(--text-primary);
}

.blocking-tab-btn.active {
  color: var(--accent);
  border-bottom-color: var(--accent);
  font-weight: 600;
}

.blocking-scroll-body {
  flex: 1;
  overflow-y: auto;
  padding: 20px 24px;
  line-height: 1.6;
}

.blocking-article h3 {
  font-size: 16px;
  margin-top: 0;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.article-meta {
  font-size: 12px;
  color: var(--text-caption);
  margin-bottom: 16px;
  padding-bottom: 10px;
  border-bottom: 1px dashed var(--border-divider);
}

.blocking-article h4 {
  font-size: 14px;
  margin-top: 16px;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.blocking-article p,
.blocking-article li {
  font-size: 13px;
  color: var(--text-secondary);
}

.blocking-article ul {
  margin: 8px 0 12px 20px;
}

.blocking-legal-footer {
  padding: 16px 24px;
  background-color: var(--bg-card-header);
  border-top: 1px solid var(--border-divider);
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.checkbox-label-text {
  font-size: 13px;
  color: var(--text-primary);
}

.blocking-action-buttons {
  display: flex;
  align-items: center;
  justify-content: flex-end;
  gap: 12px;
}

@media (max-width: 640px) {
  .blocking-legal-modal {
    max-height: 94vh;
  }
  .blocking-legal-header {
    padding: 14px 16px;
    gap: 12px;
  }
  .blocking-tabs {
    padding: 0 14px;
  }
  .blocking-tab-btn {
    font-size: 13px;
    padding: 10px 4px;
  }
  .blocking-scroll-body {
    padding: 14px 16px;
  }
  .blocking-legal-footer {
    padding: 14px 16px;
  }
  .blocking-action-buttons {
    flex-direction: column-reverse;
    align-items: stretch;
  }
  .blocking-action-buttons .fluent-btn {
    width: 100%;
    justify-content: center;
  }
}

/* Fullscreen Ad Blocker Warning Modal (全屏提示关闭广告拦截器) */
.adblock-overlay {
  position: fixed;
  inset: 0;
  z-index: 100000;
  background: rgba(0, 0, 0, 0.78);
  backdrop-filter: blur(28px);
  -webkit-backdrop-filter: blur(28px);
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  animation: fadeIn 200ms ease-out;
}

.adblock-modal {
  max-width: 640px;
  width: 100%;
  max-height: 88vh;
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-top-color: rgba(255, 255, 255, 0.45);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-dialog);
  display: flex;
  flex-direction: column;
  overflow: hidden;
  animation: dialogZoomIn 240ms var(--ease-decel);
}

[data-theme="dark"] .adblock-modal {
  border-top-color: rgba(255, 255, 255, 0.12);
}

.adblock-header {
  display: flex;
  align-items: center;
  padding: 20px 24px 16px;
  background-color: var(--bg-card-header);
  border-bottom: 1px solid var(--border-divider);
  gap: 16px;
}

.adblock-avatar {
  width: 44px;
  height: 44px;
  border-radius: var(--radius-md);
  background-color: var(--accent);
  color: #ffffff;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-shrink: 0;
  box-shadow: 0 4px 12px rgba(209, 52, 56, 0.35);
}

.adblock-heading {
  font-size: 17px;
  font-weight: 600;
  color: var(--text-primary);
  margin: 0 0 4px 0;
}

.adblock-subheading {
  font-size: 13px;
  color: var(--text-secondary);
}

.adblock-body {
  flex: 1;
  overflow-y: auto;
  padding: 20px 24px;
  line-height: 1.6;
  display: flex;
  flex-direction: column;
  gap: 14px;
}

.adblock-notice-box {
  background-color: var(--accent-tint);
  border: 1px solid rgba(209, 52, 56, 0.22);
  border-radius: var(--radius-md);
  padding: 12px 16px;
  font-size: 13px;
  color: var(--text-primary);
}

.adblock-commitments h4 {
  font-size: 14px;
  font-weight: 600;
  margin-bottom: 8px;
  color: var(--text-primary);
}

.adblock-commitments ul {
  margin: 0 0 4px 20px;
  font-size: 13px;
  color: var(--text-secondary);
}

.adblock-commitments li {
  margin-bottom: 6px;
}

.adblock-guide-box {
  background-color: var(--bg-btn);
  border: 1px solid var(--border-divider);
  border-radius: var(--radius-md);
  padding: 12px 16px;
  font-size: 13px;
  animation: fadeIn 200ms ease-out;
}

.adblock-guide-box h4 {
  font-size: 13px;
  font-weight: 600;
  margin-bottom: 6px;
  color: var(--text-primary);
}

.adblock-guide-box ol {
  margin: 0 0 0 20px;
  color: var(--text-secondary);
}

.adblock-guide-box li {
  margin-bottom: 4px;
}

.adblock-retry-msg {
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  background-color: rgba(209, 52, 56, 0.12);
  color: var(--accent);
  font-size: 13px;
  font-weight: 500;
  animation: fadeIn 150ms ease-out;
}

.adblock-footer {
  padding: 16px 24px;
  background-color: var(--bg-card-header);
  border-top: 1px solid var(--border-divider);
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.adblock-footer-right {
  display: flex;
  align-items: center;
  gap: 10px;
}

@media (max-width: 640px) {
  .adblock-modal {
    max-height: 94vh;
  }
  .adblock-header {
    padding: 14px 16px;
    gap: 12px;
  }
  .adblock-body {
    padding: 14px 16px;
  }
  .adblock-footer {
    padding: 14px 16px;
    flex-direction: column-reverse;
    align-items: stretch;
  }
  .adblock-footer-right {
    flex-direction: column-reverse;
    align-items: stretch;
  }
  .adblock-footer .fluent-btn {
    width: 100%;
    justify-content: center;
  }
}

/* Floating Cue Context Popover (浮窗操作栏 - WinUI CommandBar Flyout) */
.cue-popover {
  position: fixed;
  z-index: 2000;
  background: rgba(255, 255, 255, 0.88);
  border: 1px solid rgba(0, 0, 0, 0.1);
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-flyout);
  padding: 6px 10px;
  display: flex;
  align-items: center;
  gap: 8px;
  backdrop-filter: blur(28px) saturate(180%);
  -webkit-backdrop-filter: blur(28px) saturate(180%);
  animation: popoverFlyoutIn 180ms var(--ease-spring);
  pointer-events: auto;
}

[data-theme="dark"] .cue-popover {
  background: rgba(44, 44, 44, 0.88);
  border-color: rgba(255, 255, 255, 0.14);
}

.popover-badge {
  font-size: 11px;
  font-weight: 600;
  font-variant-numeric: tabular-nums;
  padding: 3px 6px;
  border-radius: 4px;
  background-color: var(--bg-btn);
  color: var(--accent);
  border: 1px solid var(--border-divider);
  flex-shrink: 0;
}

.popover-buttons {
  display: flex;
  align-items: center;
  gap: 6px;
}

.popover-buttons .fluent-btn {
  display: inline-flex;
  align-items: center;
  gap: 5px;
  white-space: nowrap;
}

@keyframes popoverFlyoutIn {
  from {
    opacity: 0;
    transform: scale(0.92) translateY(4px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

/* Return Original Button Floating (WinUI Pill) */
.return-btn-float {
  position: sticky;
  top: 10px;
  right: 14px;
  float: right;
  z-index: 100;
  margin-bottom: -36px;
  animation: returnPillIn 240ms var(--ease-spring);
}

@keyframes returnPillIn {
  from {
    opacity: 0;
    transform: translateY(-8px) scale(0.92);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

.return-btn-float .fluent-btn {
  box-shadow: 0 4px 14px rgba(209, 52, 56, 0.35);
  border-radius: var(--radius-pill);
  padding: 6px 14px;
  font-weight: 500;
}

/* Fluent Modal / Dialog */
.fluent-modal-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(0, 0, 0, 0.45);
  backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  z-index: 2000;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
  animation: modalFadeIn 160ms ease-out;
}

@keyframes modalFadeIn {
  from { opacity: 0; }
  to { opacity: 1; }
}

.fluent-dialog {
  background-color: var(--bg-card);
  border: 1px solid var(--border-card);
  border-top-color: rgba(255, 255, 255, 0.45);
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-dialog);
  width: 100%;
  max-width: 480px;
  display: flex;
  flex-direction: column;
  overflow: hidden;
  animation: dialogZoomIn 240ms var(--ease-decel);
}

[data-theme="dark"] .fluent-dialog {
  border-top-color: rgba(255, 255, 255, 0.12);
}

@keyframes dialogZoomIn {
  from {
    opacity: 0;
    transform: scale(0.94) translateY(6px);
  }
  to {
    opacity: 1;
    transform: scale(1) translateY(0);
  }
}

.dialog-header {
  padding: 18px 24px 12px;
  font-size: 18px;
  font-weight: 600;
  color: var(--text-primary);
}

.dialog-body {
  padding: 0 24px 20px;
  font-size: 14px;
  color: var(--text-secondary);
  line-height: 1.5;
  max-height: 60vh;
  overflow-y: auto;
}

.dialog-footer {
  padding: 14px 24px;
  background-color: var(--bg-card-header);
  border-top: 1px solid var(--border-divider);
  display: flex;
  justify-content: flex-end;
  gap: 10px;
}

.info-table {
  width: 100%;
  border-collapse: collapse;
}

.info-table td {
  padding: 6px 0;
  font-size: 13px;
  vertical-align: top;
}

.info-table td:first-child {
  width: 90px;
  color: var(--text-secondary);
  font-weight: 500;
}

.info-table td:last-child {
  color: var(--text-primary);
  word-break: break-all;
}

/* Drag and Drop Overlay */
.drop-overlay {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  background-color: rgba(209, 52, 56, 0.08);
  border: 3px dashed var(--accent);
  z-index: 3000;
  display: none;
  align-items: center;
  justify-content: center;
  pointer-events: none;
}

.drop-overlay.active {
  display: flex;
}

.drop-overlay-box {
  background-color: var(--bg-card);
  padding: 24px 40px;
  border-radius: var(--radius-lg);
  box-shadow: var(--shadow-flyout);
  font-size: 18px;
  font-weight: 600;
  color: var(--accent);
}

/* Mobile Tabs Bar */
.mobile-tabs-bar {
  display: none;
  height: 40px;
  background-color: var(--bg-card);
  border-bottom: 1px solid var(--border-divider);
  flex-shrink: 0;
}

.mobile-tab {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  font-size: 13px;
  color: var(--text-secondary);
  cursor: pointer;
  border-bottom: 2px solid transparent;
  transition: all var(--trans-fast);
}

.mobile-tab.active {
  color: var(--accent);
  font-weight: 600;
  border-bottom-color: var(--accent);
}

/* Mobile Mini Player */
.mobile-mini-player {
  display: none;
}

/* Mobile Adaptation (max-width: 860px) */
@media (max-width: 860px) {
  .app-header {
    height: 48px;
    padding: 0 12px;
  }

  .header-left {
    gap: 8px;
    min-width: 0;
    flex: 1;
  }

  .header-right {
    gap: 6px;
    flex-shrink: 0;
  }

  .header-right .fluent-btn span {
    display: none;
  }

  .header-right .fluent-btn {
    padding: 6px 8px;
  }

  .app-title {
    font-size: 15px;
    font-weight: 600;
    max-width: none;
    flex: 1;
    min-width: 0;
  }

  .app-version-badge {
    padding: 2px 6px;
    font-size: 10px;
    gap: 4px;
  }

  /* Player View Header on Mobile: Unclutter completely to maximize title */
  #app[data-view="player"] .app-version-badge {
    display: none !important;
  }

  #app[data-view="player"] .app-logo-mark {
    display: none !important;
  }

  #app[data-view="player"] .header-import-actions {
    display: none !important;
  }

  /* Mobile tabs bar only visible in player view */
  #app[data-view="home"] .mobile-tabs-bar {
    display: none !important;
  }

  #app[data-view="player"] .mobile-tabs-bar {
    display: flex;
  }

  .player-view {
    flex-direction: column;
    overflow: hidden;
  }

  .player-section {
    flex: 1;
    border-right: none;
    padding: 10px 12px 6px;
    overflow: hidden;
    height: 100%;
    box-sizing: border-box;
    display: flex;
    flex-direction: column;
  }

  .question-container {
    flex: 1 1 0;
    min-height: 0;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
  }

  .transcript-section {
    flex: 1;
    padding: 12px 14px 0;
    overflow-y: auto;
    -webkit-overflow-scrolling: touch;
    box-sizing: border-box;
  }

  /* Show / Hide according to active mobile tab */
  .player-view[data-tab="question"] .player-section {
    display: flex;
    flex-direction: column;
    padding-bottom: calc(10px + env(safe-area-inset-bottom));
  }
  .player-view[data-tab="question"] .transcript-section {
    display: none;
  }

  .player-view[data-tab="transcript"] .player-section {
    display: none;
  }
  .player-view[data-tab="transcript"] .transcript-section {
    display: flex;
  }

  /* Split View Tab on Mobile */
  .player-view[data-tab="split"] .player-section {
    display: flex;
    flex-direction: column;
    flex: 1;
    height: 50%;
    max-height: 50%;
    border-bottom: 1px solid var(--border-divider);
    overflow: hidden;
  }
  .player-view[data-tab="split"] .transcript-section {
    display: flex;
    flex: 1;
  }

  /* Sticky Mini Player in Transcript Tab */
  .player-view[data-tab="transcript"] .mobile-mini-player {
    display: flex;
    flex-direction: column;
    gap: 6px;
    position: sticky;
    bottom: 0;
    left: 0;
    right: 0;
    background-color: var(--bg-card);
    backdrop-filter: blur(16px);
    border-top: 1px solid var(--border-divider);
    padding: 8px 12px calc(8px + env(safe-area-inset-bottom));
    margin: 12px -14px 0 -14px;
    box-shadow: 0 -4px 16px rgba(0, 0, 0, 0.08);
    z-index: 100;
  }

  .mini-progress-row {
    display: flex;
    align-items: center;
    gap: 8px;
    font-size: 11px;
    color: var(--text-secondary);
  }

  .mini-controls-row {
    display: flex;
    align-items: center;
    justify-content: center;
    gap: 8px;
  }

  .lesson-row {
    height: auto;
    padding: 14px 16px;
  }

  .lesson-row-meta {
    flex-direction: column;
    align-items: flex-start;
    gap: 6px;
  }

  .progress-track {
    width: 100%;
  }

  .actions-row, .controls-row {
    gap: 6px;
  }

  .fluent-btn {
    padding: 6px 10px;
    font-size: 13px;
  }
}