/* ==========================================================================
   EnglishStar - iOS Children's English Learning App Design System
   Prototype CSS for iPhone 15 Pro simulation
   ========================================================================== */

/* --------------------------------------------------------------------------
   1. CSS Variables (Design Tokens)
   -------------------------------------------------------------------------- */
:root {
  /* Primary Colors */
  --color-primary-blue: #2563EB;
  --color-primary-red: #EF4444;
  --color-primary-green: #22C55E;
  --color-primary-orange: #F59E0B;

  /* Category Gradients (10 word categories) */
  --gradient-body: linear-gradient(135deg, #FF6B6B 0%, #FF8E8E 100%);
  --gradient-animal: linear-gradient(135deg, #4CAF50 0%, #81C784 100%);
  --gradient-food: linear-gradient(135deg, #FF9800 0%, #FFB74D 100%);
  --gradient-color: linear-gradient(135deg, #9C27B0 0%, #BA68C8 100%);
  --gradient-number: linear-gradient(135deg, #2196F3 0%, #64B5F6 100%);
  --gradient-nature: linear-gradient(135deg, #009688 0%, #4DB6AC 100%);
  --gradient-family: linear-gradient(135deg, #FFC107 0%, #FFD54F 100%);
  --gradient-action: linear-gradient(135deg, #673AB7 0%, #9575CD 100%);
  --gradient-object: linear-gradient(135deg, #F44336 0%, #E57373 100%);
  --gradient-social: linear-gradient(135deg, #03A9F4 0%, #4FC3F7 100%);

  /* Typography */
  --font-hero: 36px;
  --font-title: 24px;
  --font-body: 18px;
  --font-secondary: 15px;
  --font-caption: 13px;
  --font-stack: -apple-system, 'SF Pro Display', 'SF Pro Text', 'Helvetica Neue', sans-serif;
  --font-stack-rounded: -apple-system, 'SF Pro Rounded', 'SF Pro Display', 'Helvetica Neue', sans-serif;

  /* Spacing */
  --space-4: 4px;
  --space-8: 8px;
  --space-12: 12px;
  --space-16: 16px;
  --space-20: 20px;
  --space-24: 24px;
  --space-32: 32px;

  /* Border Radius */
  --radius-12: 12px;
  --radius-16: 16px;
  --radius-20: 20px;
  --radius-24: 24px;

  /* Shadows */
  --shadow-card: 0 2px 12px rgba(0, 0, 0, 0.08);
  --shadow-card-hover: 0 4px 20px rgba(0, 0, 0, 0.12);
  --shadow-glow: 0 0 20px rgba(255, 193, 7, 0.5);

  /* Transitions */
  --transition-fast: 0.2s ease;
  --transition-normal: 0.3s ease;
  --transition-slow: 0.5s ease;
}

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

html {
  font-size: 16px;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

body {
  font-family: var(--font-stack);
  font-size: var(--font-body);
  line-height: 1.5;
  color: #1a1a1a;
  background: #0d0d0d;
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-24);
}

/* --------------------------------------------------------------------------
   3. iPhone 15 Pro Frame
   -------------------------------------------------------------------------- */
.iphone-frame {
  width: 393px;
  height: 852px;
  background: #000;
  border-radius: 55px;
  border: 12px solid #1a1a1a;
  position: relative;
  overflow: hidden;
  box-shadow:
    0 0 0 2px #2a2a2a,
    0 25px 50px -12px rgba(0, 0, 0, 0.5),
    0 0 100px rgba(0, 0, 0, 0.3);
}

/* Dynamic Island */
.iphone-frame::before {
  content: '';
  position: absolute;
  top: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: 126px;
  height: 37px;
  background: #000;
  border-radius: 20px;
  z-index: 1000;
}

/* Home Indicator Bar */
.iphone-frame::after {
  content: '';
  position: absolute;
  bottom: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: 134px;
  height: 5px;
  background: rgba(255, 255, 255, 0.3);
  border-radius: 3px;
  z-index: 1000;
}

/* App content area (safe zone) */
.iphone-screen,
.screen {
  width: 100%;
  height: 100%;
  background: #f2f2f7;
  position: relative;
  overflow: hidden;
}

/* Dynamic Island (when used as div) */
.dynamic-island {
  position: absolute;
  top: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: 126px;
  height: 37px;
  background: #000;
  border-radius: 20px;
  z-index: 1000;
}

/* Home Indicator (when used as div) */
.home-indicator {
  position: absolute;
  bottom: 12px;
  left: 50%;
  transform: translateX(-50%);
  width: 134px;
  height: 5px;
  background: rgba(255, 255, 255, 0.3);
  border-radius: 3px;
  z-index: 1000;
}

/* Page content wrapper */
.page {
  width: 100%;
  height: 100%;
  position: relative;
  overflow-y: auto;
  overflow-x: hidden;
  padding-top: 56px;
  padding-bottom: 34px;
  -webkit-overflow-scrolling: touch;
}

/* --------------------------------------------------------------------------
   4. iOS-style Navigation Bar
   -------------------------------------------------------------------------- */
.nav-bar {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  height: 56px;
  padding: 0 var(--space-16);
  display: flex;
  align-items: center;
  justify-content: space-between;
  background: rgba(255, 255, 255, 0.72);
  backdrop-filter: blur(20px);
  -webkit-backdrop-filter: blur(20px);
  border-bottom: 0.5px solid rgba(0, 0, 0, 0.1);
  z-index: 100;
}

.nav-bar__back {
  font-size: var(--font-body);
  color: var(--color-primary-blue);
  background: none;
  border: none;
  padding: var(--space-8) 0;
  cursor: pointer;
  font-family: var(--font-stack);
}

.nav-bar__title {
  font-size: var(--font-secondary);
  font-weight: 600;
  color: #1a1a1a;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
}

.nav-bar__action {
  font-size: var(--font-body);
  color: var(--color-primary-blue);
  background: none;
  border: none;
  padding: var(--space-8) 0;
  cursor: pointer;
  font-family: var(--font-stack);
}

.nav-bar__action:disabled {
  color: #8e8e93;
  cursor: not-allowed;
}

/* --------------------------------------------------------------------------
   5. Common Components
   -------------------------------------------------------------------------- */

/* Card */
.card {
  background: #fff;
  border-radius: var(--radius-16);
  box-shadow: var(--shadow-card);
  padding: var(--space-20);
  transition: box-shadow var(--transition-normal);
}

.card:hover {
  box-shadow: var(--shadow-card-hover);
}

/* Primary Button */
.primary-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-16) var(--space-32);
  font-size: var(--font-body);
  font-weight: 600;
  font-family: var(--font-stack);
  color: #fff;
  background: linear-gradient(135deg, var(--color-primary-blue) 0%, #5856D6 100%);
  border: none;
  border-radius: var(--radius-16);
  cursor: pointer;
  transition: transform var(--transition-fast), opacity var(--transition-fast);
  box-shadow: 0 4px 12px rgba(0, 122, 255, 0.3);
}

.primary-btn:hover {
  transform: scale(1.02);
  opacity: 0.95;
}

.primary-btn:active {
  transform: scale(0.98);
}

/* Secondary Button */
.secondary-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  padding: var(--space-12) var(--space-24);
  font-size: var(--font-secondary);
  font-weight: 500;
  font-family: var(--font-stack);
  color: var(--color-primary-blue);
  background: rgba(0, 122, 255, 0.12);
  border: 1px solid rgba(0, 122, 255, 0.3);
  border-radius: var(--radius-12);
  cursor: pointer;
  transition: background var(--transition-fast), border-color var(--transition-fast);
}

.secondary-btn:hover {
  background: rgba(0, 122, 255, 0.18);
  border-color: rgba(0, 122, 255, 0.5);
}

/* Tag */
.tag {
  display: inline-flex;
  align-items: center;
  padding: var(--space-4) var(--space-12);
  font-size: var(--font-caption);
  font-weight: 500;
  font-family: var(--font-stack);
  color: #1a1a1a;
  background: rgba(0, 0, 0, 0.06);
  border-radius: var(--radius-12);
}

.tag--category-body { background: var(--gradient-body); color: #fff; }
.tag--category-animal { background: var(--gradient-animal); color: #fff; }
.tag--category-food { background: var(--gradient-food); color: #fff; }
.tag--category-color { background: var(--gradient-color); color: #fff; }
.tag--category-number { background: var(--gradient-number); color: #fff; }
.tag--category-nature { background: var(--gradient-nature); color: #fff; }
.tag--category-family { background: var(--gradient-family); color: #1a1a1a; }
.tag--category-action { background: var(--gradient-action); color: #fff; }
.tag--category-object { background: var(--gradient-object); color: #fff; }
.tag--category-social { background: var(--gradient-social); color: #fff; }

/* Toggle Switch (iOS style) */
.toggle-switch {
  position: relative;
  width: 51px;
  height: 31px;
  background: #e9e9eb;
  border-radius: 16px;
  cursor: pointer;
  transition: background var(--transition-fast);
}

.toggle-switch::after {
  content: '';
  position: absolute;
  top: 2px;
  left: 2px;
  width: 27px;
  height: 27px;
  background: #fff;
  border-radius: 50%;
  box-shadow: 0 2px 4px rgba(0, 0, 0, 0.2);
  transition: transform var(--transition-fast);
}

.toggle-switch.is-on {
  background: var(--color-primary-green);
}

.toggle-switch.is-on::after {
  transform: translateX(20px);
}

/* Stat Card */
.stat-card {
  background: #fff;
  border-radius: var(--radius-16);
  padding: var(--space-20);
  box-shadow: var(--shadow-card);
}

.stat-card__value {
  font-size: var(--font-hero);
  font-weight: 700;
  color: #1a1a1a;
  line-height: 1.2;
}

.stat-card__label {
  font-size: var(--font-caption);
  color: #8e8e93;
  margin-top: var(--space-4);
}

/* Progress Bar */
.progress-bar {
  height: 8px;
  background: rgba(0, 0, 0, 0.08);
  border-radius: 4px;
  overflow: hidden;
}

.progress-bar__fill {
  height: 100%;
  background: var(--gradient-number);
  border-radius: 4px;
  transition: width var(--transition-normal);
}

.progress-bar--animated .progress-bar__fill {
  animation: progressGrow 1s ease-out forwards;
}

@keyframes progressGrow {
  from { width: 0 !important; }
}

/* --------------------------------------------------------------------------
   6. Flashcard Component
   -------------------------------------------------------------------------- */
.flashcard {
  background: #fff;
  border-radius: var(--radius-24);
  overflow: hidden;
  box-shadow: var(--shadow-card);
  display: flex;
  flex-direction: column;
  min-height: 320px;
}

.flashcard__gradient {
  flex: 0 0 40%;
  min-height: 40%;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--space-24);
}

.flashcard--body .flashcard__gradient { background: var(--gradient-body); }
.flashcard--animal .flashcard__gradient { background: var(--gradient-animal); }
.flashcard--food .flashcard__gradient { background: var(--gradient-food); }
.flashcard--color .flashcard__gradient { background: var(--gradient-color); }
.flashcard--number .flashcard__gradient { background: var(--gradient-number); }
.flashcard--nature .flashcard__gradient { background: var(--gradient-nature); }
.flashcard--family .flashcard__gradient { background: var(--gradient-family); }
.flashcard--action .flashcard__gradient { background: var(--gradient-action); }
.flashcard--object .flashcard__gradient { background: var(--gradient-object); }
.flashcard--social .flashcard__gradient { background: var(--gradient-social); }

.flash-emoji {
  font-size: 80px;
  line-height: 1;
  margin-bottom: var(--space-8);
}

.flash-word {
  font-size: 36px;
  font-weight: 700;
  font-family: var(--font-stack-rounded);
  color: #fff;
  text-shadow: 0 2px 4px rgba(0, 0, 0, 0.1);
}

.flashcard__info {
  flex: 1;
  padding: var(--space-24);
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: #fff;
}

.flash-phonetic {
  font-size: 16px;
  color: #8e8e93;
  margin-bottom: var(--space-8);
}

.flash-chinese {
  font-size: 20px;
  font-weight: 500;
  color: #1a1a1a;
  margin-bottom: var(--space-20);
}

.play-btn {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  gap: var(--space-8);
  padding: var(--space-12) var(--space-24);
  font-size: var(--font-secondary);
  font-weight: 600;
  font-family: var(--font-stack);
  color: var(--color-primary-blue);
  background: rgba(0, 122, 255, 0.12);
  border: none;
  border-radius: 24px;
  cursor: pointer;
  transition: background var(--transition-fast);
}

.play-btn:hover {
  background: rgba(0, 122, 255, 0.2);
}

/* --------------------------------------------------------------------------
   7. Game Components
   -------------------------------------------------------------------------- */
.game-card {
  background: #fff;
  border-radius: var(--radius-16);
  padding: var(--space-20);
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: var(--space-12);
  cursor: pointer;
  border: 3px solid transparent;
  transition: all var(--transition-fast);
  box-shadow: var(--shadow-card);
}

.game-card__emoji {
  font-size: 48px;
  line-height: 1;
}

.game-card__text {
  font-size: var(--font-secondary);
  font-weight: 500;
  color: #1a1a1a;
  text-align: center;
}

.game-card:hover {
  transform: scale(1.02);
  box-shadow: var(--shadow-card-hover);
}

.game-card.is-selected {
  border-color: var(--color-primary-blue);
  box-shadow: 0 0 0 2px rgba(0, 122, 255, 0.3);
}

.game-card.is-matched {
  border-color: var(--color-primary-green);
  background: rgba(76, 175, 80, 0.08);
}

.game-card.is-matched .game-card__text {
  color: var(--color-primary-green);
}

.game-line {
  height: 3px;
  background: rgba(0, 0, 0, 0.15);
  border-radius: 2px;
  transition: all var(--transition-normal);
}

.game-line.is-matched {
  background: linear-gradient(90deg, #FFD700, #FFA500);
  box-shadow: 0 0 8px rgba(255, 215, 0, 0.5);
}

/* --------------------------------------------------------------------------
   8. Character Grid
   -------------------------------------------------------------------------- */
.character-grid {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--space-12);
  padding: var(--space-16);
  background: transparent;
}

.character-grid__cell {
  aspect-ratio: 1;
  border-radius: var(--radius-16);
  overflow: hidden;
  cursor: pointer;
  border: 3px solid transparent;
  transition: all var(--transition-normal);
  background: transparent;
}

.character-grid__cell img {
  width: 100%;
  height: 100%;
  object-fit: cover;
  display: block;
}

.character-grid__cell.is-selected {
  box-shadow: 0 0 0 4px #FFD700, 0 4px 16px rgba(255,215,0,0.4);
  z-index: 1;
}

.character-grid__cell.animate-float-in {
  animation: floatIn 0.5s ease-out forwards;
}

.character-grid__cell:nth-child(1) { animation-delay: 0.05s; }
.character-grid__cell:nth-child(2) { animation-delay: 0.1s; }
.character-grid__cell:nth-child(3) { animation-delay: 0.15s; }
.character-grid__cell:nth-child(4) { animation-delay: 0.2s; }
.character-grid__cell:nth-child(5) { animation-delay: 0.25s; }
.character-grid__cell:nth-child(6) { animation-delay: 0.3s; }
.character-grid__cell:nth-child(7) { animation-delay: 0.35s; }
.character-grid__cell:nth-child(8) { animation-delay: 0.4s; }
.character-grid__cell:nth-child(9) { animation-delay: 0.45s; }

/* --------------------------------------------------------------------------
   9. Parent Panel
   -------------------------------------------------------------------------- */

/* Parent Tab (Segmented Control) */
.parent-tab {
  display: flex;
  background: rgba(0, 0, 0, 0.06);
  border-radius: var(--radius-12);
  padding: var(--space-4);
  gap: var(--space-4);
}

.parent-tab__option {
  flex: 1;
  padding: var(--space-8) var(--space-16);
  font-size: var(--font-secondary);
  font-weight: 500;
  font-family: var(--font-stack);
  color: #8e8e93;
  background: transparent;
  border: none;
  border-radius: var(--radius-8);
  cursor: pointer;
  transition: all var(--transition-fast);
}

.parent-tab__option.is-active {
  background: #fff;
  color: #1a1a1a;
  box-shadow: var(--shadow-card);
}

/* Stat Grid */
.stat-grid {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--space-12);
}

.stat-grid .stat-card {
  margin: 0;
}

/* Setting Row (iOS Settings List Style) */
.setting-row {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--space-16) var(--space-20);
  background: #fff;
  border-bottom: 0.5px solid rgba(0, 0, 0, 0.08);
}

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

.setting-row__label {
  font-size: var(--font-body);
  color: #1a1a1a;
}

.setting-row__value {
  font-size: var(--font-secondary);
  color: #8e8e93;
}

/* Memory Bar (5-dot status indicator) */
.memory-bar {
  display: flex;
  gap: var(--space-8);
  align-items: center;
}

.memory-bar__dot {
  width: 12px;
  height: 12px;
  border-radius: 50%;
  background: rgba(0, 0, 0, 0.15);
  transition: all var(--transition-fast);
}

.memory-bar__dot.is-active {
  background: var(--color-primary-green);
  transform: scale(1.2);
}

.memory-bar__dot.is-learning {
  background: var(--color-primary-orange);
}

.memory-bar__dot.is-new {
  background: #8e8e93;
}

/* Chart Placeholder */
.chart-placeholder {
  height: 200px;
  background: linear-gradient(
    180deg,
    rgba(0, 122, 255, 0.05) 0%,
    rgba(0, 122, 255, 0.02) 100%
  );
  border-radius: var(--radius-16);
  border: 1px dashed rgba(0, 122, 255, 0.2);
  display: flex;
  align-items: center;
  justify-content: center;
  color: #8e8e93;
  font-size: var(--font-caption);
}

/* --------------------------------------------------------------------------
   10. Animations
   -------------------------------------------------------------------------- */
@keyframes floatIn {
  from {
    opacity: 0;
    transform: translateY(20px) scale(0.95);
  }
  to {
    opacity: 1;
    transform: translateY(0) scale(1);
  }
}

@keyframes fadeInUp {
  from {
    opacity: 0;
    transform: translateY(16px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

@keyframes pulse {
  0%, 100% {
    transform: scale(1);
    opacity: 1;
  }
  50% {
    transform: scale(1.03);
    opacity: 0.9;
  }
}

@keyframes shimmer {
  0% {
    background-position: -200% 0;
  }
  100% {
    background-position: 200% 0;
  }
}

.animate-float-in {
  animation: floatIn 0.5s ease-out forwards;
}

.animate-fade-in-up {
  animation: fadeInUp 0.4s ease-out forwards;
}

.animate-pulse {
  animation: pulse 2s ease-in-out infinite;
}

.animate-shimmer {
  background: linear-gradient(
    90deg,
    rgba(255, 255, 255, 0) 0%,
    rgba(255, 255, 255, 0.4) 50%,
    rgba(255, 255, 255, 0) 100%
  );
  background-size: 200% 100%;
  animation: shimmer 1.5s infinite;
}

/* Page Transitions */
.page-transition-enter {
  opacity: 0;
  transform: translateX(20px);
}

.page-transition-enter-active {
  opacity: 1;
  transform: translateX(0);
  transition: opacity var(--transition-normal), transform var(--transition-normal);
}

.page-transition-exit {
  opacity: 1;
}

.page-transition-exit-active {
  opacity: 0;
  transform: translateX(-20px);
  transition: opacity var(--transition-normal), transform var(--transition-normal);
}

/* --------------------------------------------------------------------------
   11. Responsive & Layout
   -------------------------------------------------------------------------- */
.page-container {
  display: flex;
  align-items: center;
  justify-content: center;
  min-height: 100vh;
  padding: var(--space-24);
}

/* Content area with safe zone for Dynamic Island & Home Indicator */
.app-content {
  padding-top: 56px; /* Nav bar height */
  padding-bottom: 34px; /* Home indicator clearance */
  min-height: 100%;
  overflow-y: auto;
  -webkit-overflow-scrolling: touch;
}

/* Utility: Scrollable content */
.scroll-content {
  padding: var(--space-16);
  padding-bottom: 48px;
}

/* --------------------------------------------------------------------------
   12. Utility Classes
   -------------------------------------------------------------------------- */
.text-center { text-align: center; }
.text-left { text-align: left; }
.text-right { text-align: right; }

.mt-4 { margin-top: var(--space-4); }
.mt-8 { margin-top: var(--space-8); }
.mt-12 { margin-top: var(--space-12); }
.mt-16 { margin-top: var(--space-16); }
.mt-24 { margin-top: var(--space-24); }

.mb-4 { margin-bottom: var(--space-4); }
.mb-8 { margin-bottom: var(--space-8); }
.mb-12 { margin-bottom: var(--space-12); }
.mb-16 { margin-bottom: var(--space-16); }
.mb-24 { margin-bottom: var(--space-24); }

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

/* ===== MOBILE RESPONSIVE ===== */
@media (max-width: 500px) {
  body {
    background: #FAFAFA !important;
    padding: 0 !important;
    min-height: 100vh;
  }
  .iphone-frame {
    width: 100vw !important;
    height: 100vh !important;
    border-radius: 0 !important;
    border: none !important;
    box-shadow: none !important;
  }
  .iphone-frame::before,
  .iphone-frame::after {
    display: none !important;
  }
  .dynamic-island {
    display: none !important;
  }
  .home-indicator {
    display: none !important;
  }
  .screen {
    border-radius: 0 !important;
  }
  .page {
    padding-top: 0 !important;
  }
  .nav-bar,
  .game-header,
  .sp-header {
    padding-top: 14px !important;
  }
}