/* CSS Variables - Design Tokens */
:root {
  /* Colors */
  --color-primary: #2563EB;
  --color-secondary: #10B981;
  --color-background: #FFFFFF;
  --color-background-light: #F8FAFC;
  --color-text-primary: #1F2937;
  --color-text-secondary: #6B7280;
  --color-accent-orange: #F59E0B;
  --color-error: #EF4444;
  --color-success: #10B981;

  /* Bingo specific colors */
  --color-bingo-empty: #E5E7EB;
  --color-bingo-correct: #10B981;
  --color-bingo-complete: #F59E0B;

  /* Typography */
  --font-family: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-size-heading: 24px;
  --font-size-body: 16px;
  --font-size-caption: 14px;
  --font-size-label: 12px;

  /* Spacing */
  --spacing-xs: 4px;
  --spacing-s: 8px;
  --spacing-m: 16px;
  --spacing-l: 24px;
  --spacing-xl: 32px;
  --spacing-xxl: 48px;

  /* Border radius */
  --radius-small: 6px;
  --radius-medium: 12px;
  --radius-large: 16px;

  /* Shadows */
  --shadow-elevation-1: 0 1px 3px rgba(0, 0, 0, 0.1);
  --shadow-elevation-2: 0 4px 6px rgba(0, 0, 0, 0.1);
  --shadow-pressed: inset 0 2px 4px rgba(0, 0, 0, 0.1);
  --shadow-raised: 0 4px 8px rgba(0, 0, 0, 0.15), 0 2px 4px rgba(0, 0, 0, 0.1);

  /* Transitions */
  --transition-fast: 150ms ease;
  --transition-normal: 300ms ease;
  --transition-slow: 500ms ease;
}

/* Reset and Base */
* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

html {
  font-size: 16px;
}

body {
  font-family: var(--font-family);
  font-size: var(--font-size-body);
  color: var(--color-text-primary);
  background-color: var(--color-background);
  line-height: 1.5;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Container */
.container {
  max-width: 400px;
  margin: 0 auto;
  padding: var(--spacing-m);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Screen Management */
.screen {
  display: none;
}

.screen.active {
  display: block;
}

/* Language Selection Screen */
#language-screen {
  justify-content: center;
  align-items: center;
  text-align: center;
}

/* Introduction Screen */
.intro-container {
  justify-content: center;
  padding-top: var(--spacing-xl);
  padding-bottom: var(--spacing-xl);
}

.intro-hero {
  text-align: center;
  margin-bottom: var(--spacing-xxl);
}

.intro-icon {
  font-size: 64px;
  margin-bottom: var(--spacing-m);
  animation: bounce 2s infinite;
}

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

.intro-title {
  font-size: 28px;
  font-weight: 700;
  color: var(--color-text-primary);
  margin-bottom: var(--spacing-s);
}

.intro-subtitle {
  font-size: 16px;
  color: var(--color-text-secondary);
}

.intro-steps {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-l);
  margin-bottom: var(--spacing-l);
}

.intro-step {
  display: flex;
  align-items: flex-start;
  gap: var(--spacing-m);
  padding: var(--spacing-m);
  background: var(--color-background-light);
  border-radius: var(--radius-medium);
  transition: transform var(--transition-fast);
}

.intro-step:hover {
  transform: translateX(4px);
}

.step-icon {
  font-size: 36px;
  flex-shrink: 0;
}

.step-content {
  flex: 1;
}

.step-title {
  font-size: 18px;
  font-weight: 600;
  color: var(--color-text-primary);
  margin-bottom: 4px;
}

.step-text {
  font-size: 14px;
  color: var(--color-text-secondary);
  line-height: 1.5;
}

.intro-tip {
  background: #FEF3C7;
  border-left: 4px solid var(--color-accent-orange);
  padding: var(--spacing-m);
  border-radius: var(--radius-small);
  margin-bottom: var(--spacing-l);
}

.tip-text {
  font-size: 14px;
  color: var(--color-text-primary);
  margin: 0;
}

.btn-large {
  width: 100%;
  padding: var(--spacing-m);
  font-size: 18px;
  font-weight: 600;
}

.btn-pulse {
  animation: pulse 2s infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.02); }
}

.title {
  font-size: var(--font-size-heading);
  font-weight: 700;
  color: var(--color-primary);
  margin-bottom: var(--spacing-s);
  margin-top: var(--spacing-xl);
}

.subtitle {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xs);
}

.subtitle-zh {
  font-size: var(--font-size-body);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xl);
}

.language-buttons {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-m);
  width: 100%;
  max-width: 280px;
  margin: 0 auto;
}

.language-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-m);
  padding: var(--spacing-l) var(--spacing-xl);
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-medium);
  background: var(--color-background);
  color: var(--color-primary);
  font-family: var(--font-family);
  font-size: var(--font-size-body);
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 44px;
}

.language-btn:hover {
  background: var(--color-primary);
  color: var(--color-background);
  box-shadow: var(--shadow-elevation-2);
}

.lang-icon {
  font-size: 20px;
}

.lang-text {
  font-weight: 500;
}

/* Game Screen */
.game-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-xl);
  padding: var(--spacing-m) 0 var(--spacing-l) 0;
  border-bottom: 1px solid var(--color-bingo-empty);
}

.game-title {
  font-size: 24px;
  font-weight: 700;
  color: var(--color-primary);
  line-height: 1.2;
}

.header-actions {
  display: flex;
  gap: var(--spacing-m);
  align-items: center;
}

.icon-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 4px 6px;
  border: 1px solid var(--color-text-secondary);
  border-radius: var(--radius-small);
  background: var(--color-background);
  font-size: 10px;
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--color-text-secondary);
  white-space: nowrap;
  font-family: var(--font-family);
  line-height: 1;
  min-height: 28px;
}

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

.icon-btn:active {
  background: var(--color-bingo-empty);
}

/* Reset button styling */
#reset-btn:hover {
  border-color: var(--color-error);
  color: var(--color-error);
}

/* Game Info */
.game-info {
  margin-bottom: var(--spacing-xl);
}

.game-instruction {
  text-align: center;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-m);
}

.game-stats {
  display: flex;
  justify-content: space-between;
  padding: var(--spacing-s);
  background: var(--color-background-light);
  border-radius: var(--radius-small);
  font-size: var(--font-size-label);
  opacity: 0.8;
}

.stat {
  font-weight: 400;
  color: var(--color-text-secondary);
}

/* Bingo Board */
.bingo-board {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: var(--spacing-s);
  margin-bottom: var(--spacing-l);
  aspect-ratio: 1;
}

.bingo-cell {
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-s);
  border: 1px solid var(--color-bingo-empty);
  border-radius: var(--radius-medium);
  background: linear-gradient(145deg, #ffffff 0%, #f8fafc 100%);
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 80px;
  text-align: center;
  box-shadow: var(--shadow-raised);
  position: relative;
  transform: translateY(0);
}

.bingo-cell:hover {
  border-color: var(--color-primary);
  box-shadow: 0 6px 12px rgba(0, 0, 0, 0.2), 0 3px 6px rgba(0, 0, 0, 0.15);
  transform: translateY(-2px);
}

.bingo-cell.completed {
  background: linear-gradient(145deg, var(--color-bingo-correct) 0%, #0d9659 100%);
  border-color: var(--color-bingo-correct);
  color: var(--color-background);
  cursor: not-allowed;
  pointer-events: none;
  box-shadow: var(--shadow-pressed);
  transform: translateY(1px);
}

.bingo-cell.bingo-line {
  background: linear-gradient(145deg, var(--color-bingo-complete) 0%, #d97706 100%);
  border-color: var(--color-bingo-complete);
  color: var(--color-background);
  animation: bingoGlow var(--transition-slow) ease-in-out;
  box-shadow: 0 0 20px rgba(245, 158, 11, 0.4), var(--shadow-raised);
}

.bingo-cell:active {
  transform: translateY(2px) scale(0.98);
  box-shadow: var(--shadow-pressed);
  transition: all 0.1s ease;
}

@keyframes bingoGlow {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.05); }
}

@keyframes wrongAnswer {
  0% { background: var(--color-background); border-color: var(--color-bingo-empty); }
  25% { background: var(--color-error); border-color: var(--color-error); color: var(--color-background); }
  50% { background: var(--color-error); border-color: var(--color-error); color: var(--color-background); opacity: 1; }
  75% { background: var(--color-error); border-color: var(--color-error); color: var(--color-background); opacity: 0; }
  100% { background: var(--color-background); border-color: var(--color-bingo-empty); color: var(--color-text-primary); opacity: 0; }
}

@keyframes fadeInNewSpot {
  0% { opacity: 0; transform: scale(0.9); }
  100% { opacity: 1; transform: scale(1); }
}

.bingo-cell.wrong-flash {
  animation: wrongAnswer 1.2s ease-in-out;
}

.bingo-cell.fade-in-new {
  animation: fadeInNewSpot 0.5s ease-out;
}

.cell-name {
  font-size: var(--font-size-caption);
  font-weight: 500;
  line-height: 1.2;
  height: 2.4em;
  display: -webkit-box;
  -webkit-box-orient: vertical;
  -webkit-line-clamp: 2;
  overflow: hidden;
  text-overflow: ellipsis;
  text-align: center;
  margin-bottom: var(--spacing-xs);
}

.cell-distance {
  font-size: var(--font-size-caption);
  opacity: 0.9;
  font-weight: 500;
}

.cell-compass {
  font-size: 16px;
  margin-top: var(--spacing-xs);
  transition: transform 0.3s ease;
  display: inline-block;
  transform: translateY(2px);
}

.cell-compass-disabled {
  font-size: 14px;
  margin-top: var(--spacing-xs);
  opacity: 0.6;
  display: inline-block;
}

.cell-completed-icon {
  font-size: 18px;
  margin-top: var(--spacing-xs);
  color: var(--color-background);
  display: inline-block;
  transform: translateY(2px);
}

/* Location Info */
.location-info {
  margin-top: auto;
  padding: var(--spacing-m) var(--spacing-xs);
  text-align: center;
}

.location-text {
  font-size: 10px;
  color: var(--color-text-secondary);
  opacity: 0.6;
  font-weight: 300;
}

.location-icon {
  margin-right: var(--spacing-xs);
  opacity: 0.5;
}

/* Modal Styles */
.modal {
  display: none;
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.5);
  z-index: 1000;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-m);
}

.modal.active {
  display: flex;
}

.modal-content {
  background: var(--color-background);
  border-radius: var(--radius-large);
  box-shadow: var(--shadow-elevation-2);
  width: 100%;
  max-width: 400px;
  max-height: 80vh;
  overflow-y: auto;
}

.modal-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: var(--spacing-l);
  border-bottom: 1px solid var(--color-bingo-empty);
}

.modal-actions {
  display: flex;
  gap: var(--spacing-s);
  align-items: center;
}

.modal-title {
  font-size: 18px;
  font-weight: 700;
  color: var(--color-primary);
}

.close-btn {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 32px;
  height: 32px;
  border: none;
  background: none;
  font-size: 18px;
  cursor: pointer;
  border-radius: var(--radius-small);
  transition: background var(--transition-fast);
}

.close-btn:hover {
  background: var(--color-background-light);
}

.modal-body {
  padding: var(--spacing-l);
}

/* Spot Detail Modal */
.spot-info {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-l);
}

.distance-info {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: var(--spacing-l);
  padding: var(--spacing-l);
  background: var(--color-background-light);
  border-radius: var(--radius-medium);
}

.compass {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 80px;
  height: 80px;
  border: 3px solid var(--color-primary);
  border-radius: 50%;
  background: linear-gradient(135deg, var(--color-background) 0%, var(--color-background-light) 100%);
  position: relative;
  box-shadow: var(--shadow-elevation-2);
}


.compass-needle {
  font-size: 32px;
  color: var(--color-primary);
  transition: transform 0.2s ease;
  filter: drop-shadow(0 1px 2px rgba(0,0,0,0.2));
  font-weight: bold;
  transform: translateY(4px);
}

.distance-text {
  text-align: center;
}

.distance-value {
  display: block;
  font-size: 20px;
  font-weight: 700;
  color: var(--color-primary);
}

.direction-text {
  font-size: var(--font-size-caption);
  color: var(--color-text-secondary);
}


/* Quiz Section */
.quiz-section {
  text-align: center;
}

.quiz-title {
  font-size: var(--font-size-body);
  font-weight: 600;
  margin-bottom: var(--spacing-m);
  color: var(--color-text-primary);
}

.quiz-description {
  font-size: var(--font-size-caption);
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-l);
  line-height: 1.4;
}

.quiz-options {
  display: grid;
  grid-template-columns: repeat(2, 1fr);
  gap: var(--spacing-m);
}

.quiz-option {
  display: flex;
  align-items: center;
  justify-content: center;
  height: 60px;
  border: 2px solid var(--color-primary);
  border-radius: var(--radius-medium);
  background: var(--color-background);
  color: var(--color-primary);
  font-family: var(--font-family);
  font-size: 20px;
  font-weight: 700;
  cursor: pointer;
  transition: all var(--transition-fast);
  -webkit-tap-highlight-color: transparent;
  outline: none;
}

.quiz-option:hover {
  background: var(--color-primary);
  color: var(--color-background);
}

.quiz-option:active,
.quiz-option:focus {
  background: var(--color-background);
  color: var(--color-primary);
  border-color: var(--color-primary);
}

.quiz-option.correct {
  background: var(--color-success) !important;
  border-color: var(--color-success) !important;
  color: var(--color-background) !important;
}

.quiz-option.incorrect {
  background: var(--color-error) !important;
  border-color: var(--color-error) !important;
  color: var(--color-background) !important;
}

.quiz-option.selected {
  background: var(--color-text-secondary) !important;
  border-color: var(--color-text-secondary) !important;
  color: var(--color-background) !important;
}

/* Success Modal */
.success-content {
  text-align: center;
}

.success-message {
  margin-bottom: var(--spacing-xl);
}

.success-text {
  font-size: var(--font-size-body);
  font-weight: 600;
  color: var(--color-success);
  margin-bottom: var(--spacing-m);
}

.reward-text {
  font-size: var(--font-size-caption);
  color: var(--color-text-secondary);
  line-height: 1.4;
}

.success-actions,
.confirmation-actions {
  display: flex;
  flex-direction: column;
  gap: var(--spacing-m);
}

/* Buttons */
.btn {
  display: flex;
  align-items: center;
  justify-content: center;
  padding: var(--spacing-m) var(--spacing-l);
  border: 2px solid transparent;
  border-radius: var(--radius-small);
  font-family: var(--font-family);
  font-size: var(--font-size-body);
  font-weight: 500;
  cursor: pointer;
  transition: all var(--transition-fast);
  min-height: 44px;
}

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

.btn-primary:hover {
  background: #1D4ED8;
  border-color: #1D4ED8;
}

.btn-secondary {
  background: var(--color-background);
  color: var(--color-text-primary);
  border-color: var(--color-bingo-empty);
}

.btn-secondary:hover {
  background: var(--color-background-light);
  border-color: var(--color-text-secondary);
}

/* Reset Confirmation Modal */
.confirmation-text {
  text-align: center;
  color: var(--color-text-secondary);
  margin-bottom: var(--spacing-xl);
  line-height: 1.4;
}

/* Mobile touch improvements */
@media (hover: none) and (pointer: coarse) {
  /* Disable hover effects on touch devices */
  .language-btn:hover,
  .icon-btn:hover,
  .bingo-cell:hover,
  .quiz-option:hover,
  .btn-primary:hover,
  .btn-secondary:hover,
  .close-btn:hover,
  #reset-btn:hover {
    background: revert;
    border-color: revert;
    color: revert;
    box-shadow: revert;
  }

  /* Improve tap targets for mobile */
  .btn {
    min-height: 48px;
    padding: var(--spacing-m) var(--spacing-l);
  }

  .icon-btn {
    min-width: 44px;
    min-height: 44px;
    padding: var(--spacing-s);
  }

  .language-btn {
    min-height: 60px;
  }

  .quiz-option {
    min-height: 48px;
    min-width: 48px;
  }

  .bingo-cell {
    min-height: 80px;
  }

  /* Add touch feedback */
  .btn:active,
  .icon-btn:active,
  .language-btn:active,
  .quiz-option:active,
  .bingo-cell:active {
    transform: translateY(2px) scale(0.98);
    box-shadow: var(--shadow-pressed);
    transition: all 0.1s ease;
  }
}

/* Improve touch responsiveness */
.btn,
.icon-btn,
.language-btn,
.quiz-option,
.bingo-cell {
  -webkit-tap-highlight-color: transparent;
  touch-action: manipulation;
  user-select: none;
}

/* Responsive Design */
@media (max-width: 480px) {
  .container {
    padding: var(--spacing-s);
  }

  .modal {
    padding: var(--spacing-s);
  }

  .bingo-cell {
    min-height: 70px;
    padding: var(--spacing-xs);
  }

  .cell-name {
    font-size: 11px;
  }

  .cell-distance {
    font-size: 10px;
  }

  .compass {
    width: 50px;
    height: 50px;
  }

  .compass-needle {
    font-size: 20px;
  }

  .distance-value {
    font-size: 18px;
  }
}

/* Accessibility */
@media (prefers-reduced-motion: reduce) {
  * {
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
    transition-duration: 0.01ms !important;
  }
}

/* Focus indicators */
button:focus,
.bingo-cell:focus {
  outline: 2px solid var(--color-primary);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --color-primary: #0000FF;
    --color-success: #008000;
    --color-error: #FF0000;
  }
}