:root {
  --primary-color: #2196F3;
  --secondary-color: #4CAF50;
  --accent-color: #FFC107;
  --danger-color: #F44336;
  --purple-color: #9C27B0;
  --background: #0a0a0a;
  --surface: rgba(255, 255, 255, 0.1);
  --surface-light: rgba(255, 255, 255, 0.15);
  --text-primary: #ffffff;
  --text-secondary: rgba(255, 255, 255, 0.7);
  --border: rgba(255, 255, 255, 0.2);
  --shadow: 0 8px 32px rgba(0, 0, 0, 0.3);
  --glow: 0 0 20px;
}

/* Screen reader only class for accessibility */
.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;
}

* {
  margin: 0;
  padding: 0;
  box-sizing: border-box;
}

/* Performance optimizations */
* {
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}

/* Optimize animations */
.icon-btn,
.mode-btn,
.control-btn,
.action-btn,
.secondary-btn,
.danger-btn,
.export-btn {
  will-change: transform;
  transform: translateZ(0);
}

body {
  font-family: 'Segoe UI', Tahoma, Geneva, Verdana, sans-serif;
  background: linear-gradient(135deg, #0a0a0a 0%, #1a1a2e 50%, #16213e 100%);
  color: var(--text-primary);
  overflow-x: hidden;
  min-height: 100vh;
  position: relative;
}

body::before {
  content: '';
  position: fixed;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: 
    radial-gradient(circle at 20% 80%, rgba(33, 150, 243, 0.3) 0%, transparent 50%),
    radial-gradient(circle at 80% 20%, rgba(156, 39, 176, 0.3) 0%, transparent 50%),
    radial-gradient(circle at 40% 40%, rgba(76, 175, 80, 0.2) 0%, transparent 50%);
  pointer-events: none;
  z-index: -1;
}

.app-container {
  min-height: 100vh;
  display: flex;
  flex-direction: column;
  padding-bottom: 80px;
}

.app-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  padding: 1rem;
  background: var(--surface);
  backdrop-filter: blur(20px);
  border-bottom: 1px solid var(--border);
  position: sticky;
  top: 0;
  z-index: 100;
}

.app-header h1 {
  font-size: 1.5rem;
  background: linear-gradient(135deg, var(--primary-color), var(--purple-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.header-controls {
  display: flex;
  gap: 0.5rem;
}

.icon-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.3s ease;
  backdrop-filter: blur(10px);
}

.icon-btn:hover {
  background: var(--surface-light);
  box-shadow: var(--glow) rgba(33, 150, 243, 0.3);
  transform: translateY(-2px);
}

.main-content {
  flex: 1;
  padding: 1rem;
}

.content-section {
  display: none;
  animation: fadeIn 0.3s ease;
}

.content-section.active {
  display: block;
}

@keyframes fadeIn {
  from { opacity: 0; transform: translateY(20px); }
  to { opacity: 1; transform: translateY(0); }
}

.welcome-card {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 2rem;
  text-align: center;
  margin-bottom: 2rem;
  box-shadow: var(--shadow);
}

.welcome-card h2 {
  margin-bottom: 1rem;
  font-size: 1.8rem;
  background: linear-gradient(135deg, var(--primary-color), var(--secondary-color));
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

.welcome-card p {
  color: var(--text-secondary);
  margin-bottom: 2rem;
  line-height: 1.6;
}

.game-modes {
  display: flex;
  flex-direction: column;
  gap: 1rem;
}

.mode-btn {
  background: linear-gradient(135deg, var(--surface), var(--surface-light));
  border: 1px solid var(--border);
  border-radius: 15px;
  padding: 1rem;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 1rem;
  font-size: 1.1rem;
  backdrop-filter: blur(10px);
}

.mode-btn:hover {
  transform: translateY(-3px);
  box-shadow: var(--glow) rgba(33, 150, 243, 0.4);
  background: linear-gradient(135deg, var(--surface-light), var(--surface));
}

.mode-btn i {
  font-size: 1.5rem;
  color: var(--primary-color);
}

.stats-preview {
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  gap: 1rem;
  margin-bottom: 2rem;
}

.stat-item {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 15px;
  padding: 1rem;
  text-align: center;
  box-shadow: var(--shadow);
}

.stat-value {
  display: block;
  font-size: 1.5rem;
  font-weight: bold;
  color: var(--primary-color);
  margin-bottom: 0.5rem;
}

.stat-label {
  font-size: 0.9rem;
  color: var(--text-secondary);
}

.game-header {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 15px;
  padding: 1rem;
}

.game-info {
  display: flex;
  flex-direction: column;
  gap: 0.5rem;
  font-size: 0.9rem;
}

.game-info span {
  color: var(--text-secondary);
}

.game-info span span {
  color: var(--primary-color);
  font-weight: bold;
}

.game-area {
  position: relative;
  display: flex;
  justify-content: center;
  align-items: center;
  margin-bottom: 2rem;
  min-height: 400px;
}

#game-canvas {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 2px solid var(--border);
  border-radius: 20px;
  box-shadow: var(--shadow);
  max-width: 100%;
  height: auto;
  cursor: pointer;
  display: block;
  margin: 0 auto;
}

.game-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(10px);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: 20px;
  transition: opacity 0.3s ease;
}

.game-overlay.hidden {
  opacity: 0;
  pointer-events: none;
  visibility: hidden;
}

.overlay-content {
  text-align: center;
  color: var(--text-primary);
}

.countdown {
  font-size: 4rem;
  font-weight: bold;
  color: var(--accent-color);
  text-shadow: var(--glow) var(--accent-color);
  margin: 1rem 0;
  animation: pulse 1s infinite;
}

@keyframes pulse {
  0%, 100% { transform: scale(1); }
  50% { transform: scale(1.1); }
}

.game-controls {
  display: flex;
  justify-content: space-between;
  gap: 1rem;
}

.control-btn {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 15px;
  padding: 1rem;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 0.5rem;
  backdrop-filter: blur(10px);
}

.control-btn:hover {
  background: var(--surface-light);
  transform: translateY(-2px);
  box-shadow: var(--glow) rgba(33, 150, 243, 0.3);
}

.control-btn.primary {
  background: linear-gradient(135deg, var(--secondary-color), #45a049);
  border-color: var(--secondary-color);
}

.control-btn.primary:hover {
  box-shadow: var(--glow) rgba(76, 175, 80, 0.4);
}

.action-btn {
  background: linear-gradient(135deg, var(--primary-color), #1976D2);
  border: none;
  border-radius: 15px;
  padding: 1rem 2rem;
  color: white;
  font-size: 1.1rem;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  box-shadow: var(--shadow);
}

.action-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--glow) rgba(33, 150, 243, 0.4);
}

.secondary-btn {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 15px;
  padding: 1rem 2rem;
  color: var(--text-primary);
  font-size: 1.1rem;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  backdrop-filter: blur(10px);
}

.secondary-btn:hover {
  background: var(--surface-light);
  transform: translateY(-2px);
}

.stats-grid {
  display: grid;
  grid-template-columns: repeat(auto-fit, minmax(150px, 1fr));
  gap: 1rem;
  margin-bottom: 2rem;
}

.stat-card {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 1.5rem;
  text-align: center;
  box-shadow: var(--shadow);
  transition: transform 0.3s ease;
}

.stat-card:hover {
  transform: translateY(-5px);
}

.stat-card i {
  font-size: 2rem;
  color: var(--primary-color);
  margin-bottom: 1rem;
}

.stat-card h3 {
  font-size: 1.8rem;
  margin-bottom: 0.5rem;
  color: var(--accent-color);
}

.stat-card p {
  color: var(--text-secondary);
  font-size: 0.9rem;
}

.performance-chart {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 1.5rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow);
}

.performance-chart h3 {
  margin-bottom: 1rem;
  color: var(--primary-color);
}

#performance-canvas {
  width: 100%;
  height: 200px;
  background: rgba(255, 255, 255, 0.05);
  border-radius: 10px;
}

.export-controls {
  display: flex;
  gap: 1rem;
}

.export-btn {
  flex: 1;
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 15px;
  padding: 1rem;
  color: var(--text-primary);
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 0.5rem;
  backdrop-filter: blur(10px);
}

.export-btn:hover {
  background: var(--surface-light);
  transform: translateY(-2px);
  box-shadow: var(--glow) rgba(33, 150, 243, 0.3);
}

.settings-group {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 1.5rem;
  margin-bottom: 2rem;
  box-shadow: var(--shadow);
}

.settings-group h3 {
  margin-bottom: 1rem;
  color: var(--primary-color);
}

.setting-item {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: 1rem;
  padding: 1rem 0;
  border-bottom: 1px solid var(--border);
}

.setting-item:last-child {
  border-bottom: none;
  margin-bottom: 0;
}

.setting-item label {
  color: var(--text-primary);
  font-weight: 500;
}

.setting-item input[type="range"] {
  width: 100px;
  margin: 0 10px;
}

.setting-item input[type="checkbox"] {
  width: 20px;
  height: 20px;
  accent-color: var(--primary-color);
}

.setting-item select {
  background: var(--surface);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 0.5rem;
  color: var(--text-primary);
}

.danger-btn {
  background: linear-gradient(135deg, var(--danger-color), #d32f2f);
  border: none;
  border-radius: 15px;
  padding: 1rem 2rem;
  color: white;
  cursor: pointer;
  transition: all 0.3s ease;
  display: flex;
  align-items: center;
  gap: 0.5rem;
  margin-right: 1rem;
}

.danger-btn:hover {
  transform: translateY(-2px);
  box-shadow: var(--glow) rgba(244, 67, 54, 0.4);
}

.faq-container {
  max-width: 800px;
  margin: 0 auto;
}

.faq-item {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 15px;
  margin-bottom: 1rem;
  overflow: hidden;
  box-shadow: var(--shadow);
}

.faq-question {
  width: 100%;
  background: none;
  border: none;
  padding: 1.5rem;
  text-align: left;
  color: var(--text-primary);
  font-size: 1.1rem;
  font-weight: 500;
  cursor: pointer;
  display: flex;
  justify-content: space-between;
  align-items: center;
  transition: background 0.3s ease;
}

.faq-question:hover {
  background: var(--surface-light);
}

.faq-icon {
  font-size: 1.5rem;
  color: var(--primary-color);
  transition: transform 0.3s ease;
}

.faq-question[aria-expanded="true"] .faq-icon {
  transform: rotate(45deg);
}

.faq-answer {
  padding: 0 1.5rem 1.5rem;
  color: var(--text-secondary);
  line-height: 1.6;
  animation: slideDown 0.3s ease;
}

.faq-answer[hidden] {
  display: none;
}

@keyframes slideDown {
  from {
    opacity: 0;
    transform: translateY(-10px);
  }
  to {
    opacity: 1;
    transform: translateY(0);
  }
}

.bottom-nav {
  position: fixed;
  bottom: 0;
  left: 0;
  right: 0;
  background: var(--surface);
  backdrop-filter: blur(20px);
  border-top: 1px solid var(--border);
  display: flex;
  justify-content: space-around;
  padding: 0.5rem 0;
  z-index: 1000;
  visibility: visible;
  opacity: 1;
}

.nav-item {
  display: flex;
  flex-direction: column;
  align-items: center;
  padding: 0.5rem;
  color: var(--text-secondary);
  text-decoration: none;
  transition: all 0.3s ease;
  border-radius: 10px;
  min-width: 60px;
  cursor: pointer;
  user-select: none;
}

.nav-item:hover,
.nav-item.active {
  color: var(--primary-color);
  background: rgba(33, 150, 243, 0.1);
  transform: translateY(-2px);
}

.nav-item i {
  font-size: 1.2rem;
  margin-bottom: 0.25rem;
}

.nav-item span {
  font-size: 0.7rem;
  font-weight: 500;
}

.modal {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.8);
  backdrop-filter: blur(10px);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 2000;
  transition: opacity 0.3s ease;
}

.modal.hidden {
  opacity: 0;
  pointer-events: none;
}

.modal-content {
  background: var(--surface);
  backdrop-filter: blur(20px);
  border: 1px solid var(--border);
  border-radius: 20px;
  padding: 2rem;
  max-width: 90vw;
  max-height: 90vh;
  overflow-y: auto;
  box-shadow: var(--shadow);
  text-align: center;
}

.modal-content h3 {
  margin-bottom: 1.5rem;
  color: var(--primary-color);
  font-size: 1.5rem;
}

.game-results {
  margin: 2rem 0;
}

.result-item {
  display: flex;
  justify-content: space-between;
  margin-bottom: 1rem;
  padding: 0.5rem 0;
  border-bottom: 1px solid var(--border);
}

.result-item:last-child {
  border-bottom: none;
}

.modal-actions {
  display: flex;
  gap: 1rem;
  justify-content: center;
  flex-wrap: wrap;
}

.hidden {
  display: none !important;
}

footer {
  text-align: center;
  padding: 1rem;
  color: var(--text-secondary);
  font-size: 0.9rem;
  border-top: 1px solid var(--border);
  background: var(--surface);
  backdrop-filter: blur(20px);
}

@media (max-width: 768px) {
  .game-modes {
    gap: 0.75rem;
  }
  
  .mode-btn {
    padding: 0.75rem;
    font-size: 1rem;
  }
  
  .stats-preview {
    grid-template-columns: 1fr;
    gap: 0.75rem;
  }
  
  .game-controls {
    flex-direction: column;
    gap: 0.75rem;
  }
  
  .control-btn {
    flex-direction: row;
    justify-content: center;
    padding: 0.75rem;
  }
  
  .export-controls {
    flex-direction: column;
  }
  
  .modal-actions {
    flex-direction: column;
  }
  
  .setting-item {
    flex-direction: column;
    align-items: flex-start;
    gap: 0.5rem;
  }
  
  .setting-item input[type="range"] {
    width: 100%;
    margin: 0;
  }
}

@media (max-width: 480px) {
  .main-content {
    padding: 0.75rem;
  }
  
  .welcome-card {
    padding: 1.5rem;
  }
  
  .app-header h1 {
    font-size: 1.25rem;
  }
  
  .stats-grid {
    grid-template-columns: repeat(2, 1fr);
  }
  
  .game-info {
    font-size: 0.8rem;
  }
  
  #game-canvas {
    width: 280px;
    height: 280px;
  }
}

/* Focus styles for accessibility */
.icon-btn:focus,
.mode-btn:focus,
.control-btn:focus,
.action-btn:focus,
.secondary-btn:focus,
.danger-btn:focus,
.export-btn:focus,
input:focus,
select:focus {
  outline: 2px solid var(--primary-color);
  outline-offset: 2px;
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --surface: rgba(255, 255, 255, 0.2);
    --surface-light: rgba(255, 255, 255, 0.25);
    --border: rgba(255, 255, 255, 0.4);
  }
}

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