/* Fancy2048 - Modern CSS with CSS Variables and Advanced Features */

:root {
  /* Color Palette */
  --primary-color: #1a1a1a;
  --secondary-color: #ffcc00;
  --accent-color: #ff6b35;
  --background-color: #fafafa;
  --surface-color: #ffffff;
  --text-primary: #333333;
  --text-secondary: #666666;
  --text-light: #999999;
  --border-color: #e0e0e0;
  --shadow-color: rgba(0, 0, 0, 0.1);
  --success-color: #4caf50;
  --warning-color: #ff9800;
  --error-color: #f44336;
  
  /* Dark Theme Colors */
  --dark-primary: #ffffff;
  --dark-secondary: #ffcc00;
  --dark-background: #0f0f0f;
  --dark-surface: #1a1a1a;
  --dark-text-primary: #ffffff;
  --dark-text-secondary: #cccccc;
  --dark-border: #404040;
  --dark-shadow: rgba(255, 255, 255, 0.15);
  
  /* Typography */
  --font-family-primary: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, 'Helvetica Neue', Arial, sans-serif;
  --font-family-mono: 'SF Mono', Monaco, 'Cascadia Code', 'Roboto Mono', Consolas, monospace;
  --font-size-xs: 0.75rem;
  --font-size-sm: 0.875rem;
  --font-size-base: 1rem;
  --font-size-lg: 1.125rem;
  --font-size-xl: 1.25rem;
  --font-size-2xl: 1.5rem;
  --font-size-3xl: 1.875rem;
  --font-size-4xl: 2.25rem;
  
  /* Spacing */
  --spacing-xs: 0.25rem;
  --spacing-sm: 0.5rem;
  --spacing-md: 1rem;
  --spacing-lg: 1.5rem;
  --spacing-xl: 2rem;
  --spacing-2xl: 3rem;
  
  /* Breakpoints */
  --bp-sm: 640px;
  --bp-md: 768px;
  --bp-lg: 1024px;
  --bp-xl: 1280px;
  
  /* Animation */
  --transition-fast: 0.15s ease-out;
  --transition-base: 0.25s ease-out;
  --transition-slow: 0.35s ease-out;
  --transition-smooth: 0.3s cubic-bezier(0.25, 0.46, 0.45, 0.94);
  --transition-bounce: 0.4s cubic-bezier(0.68, -0.55, 0.265, 1.55);
  
  /* Board */
  --board-size: min(400px, 90vw);
  --tile-size: calc((var(--board-size) - 60px) / 4);
  --tile-gap: 12px;
  --tile-radius: 8px;
  
  /* Z-indexes */
  --z-dropdown: 1000;
  --z-sticky: 1020;
  --z-fixed: 1030;
  --z-modal-backdrop: 1040;
  --z-modal: 1050;
  --z-popover: 1060;
  --z-tooltip: 1070;
}

/* Dark theme */
[data-theme="dark"] {
  --primary-color: var(--dark-primary);
  --background-color: var(--dark-background);
  --surface-color: var(--dark-surface);
  --text-primary: var(--dark-text-primary);
  --text-secondary: var(--dark-text-secondary);
  --border-color: var(--dark-border);
  --shadow-color: var(--dark-shadow);
}

/* Reset and base styles */
*,
*::before,
*::after {
  box-sizing: border-box;
}

html {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
  text-rendering: optimizeLegibility;
}

body {
  margin: 0;
  padding: 0;
  font-family: var(--font-family-primary);
  font-size: var(--font-size-base);
  line-height: 1.6;
  color: var(--text-primary);
  background-color: var(--background-color);
  transition: background-color var(--transition-base), color var(--transition-base);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Skip link for accessibility */
.skip-link {
  position: absolute;
  top: -40px;
  left: 6px;
  background: var(--primary-color);
  color: white;
  padding: 8px;
  text-decoration: none;
  border-radius: 4px;
  z-index: var(--z-tooltip);
  transition: top var(--transition-fast);
}

.skip-link:focus {
  top: 6px;
}

/* Container */
.container {
  max-width: 1200px;
  margin: 0 auto;
  padding: 0 var(--spacing-md);
}

/* Header */
.header {
  background: var(--surface-color);
  border-bottom: 1px solid var(--border-color);
  box-shadow: 0 2px 4px var(--shadow-color);
  position: sticky;
  top: 0;
  z-index: var(--z-sticky);
  transition: all var(--transition-base);
}

.header .container {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: var(--spacing-md);
  min-height: 64px;
}

.game-title {
  margin: 0;
  font-size: var(--font-size-2xl);
  font-weight: 700;
  color: var(--primary-color);
  display: flex;
  flex-direction: column;
  line-height: 1.2;
}

.title-text {
  color: var(--primary-color);
}

.title-subtitle {
  font-size: var(--font-size-xs);
  color: var(--text-secondary);
  font-weight: 400;
  text-transform: uppercase;
  letter-spacing: 0.5px;
}

.header-nav {
  display: flex;
  gap: var(--spacing-sm);
}

.nav-button {
  background: none;
  border: 1px solid var(--border-color);
  border-radius: 50%;
  width: 40px;
  height: 40px;
  display: flex;
  align-items: center;
  justify-content: center;
  cursor: pointer;
  transition: all var(--transition-fast);
  color: var(--text-secondary);
}

.nav-button:hover {
  background: var(--border-color);
  transform: scale(1.05);
}

.nav-button:active {
  transform: scale(0.95);
}

.nav-button.danger {
  border-color: var(--error-color);
  color: var(--error-color);
}

.nav-button.danger:hover {
  background: var(--error-color);
  color: white;
}

/* Main content */
.main-content {
  flex: 1;
  padding: var(--spacing-xl) 0;
}

/* Game Info Panel */
.game-info {
  display: flex;
  justify-content: space-between;
  align-items: center;
  margin-bottom: var(--spacing-xl);
  gap: var(--spacing-md);
  flex-wrap: wrap;
}

.score-panel {
  display: flex;
  gap: var(--spacing-md);
}

.score-item {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: var(--tile-radius);
  padding: var(--spacing-md);
  text-align: center;
  min-width: 80px;
  box-shadow: 0 2px 4px var(--shadow-color);
  transition: all var(--transition-base);
}

.score-item:hover {
  transform: translateY(-2px);
  box-shadow: 0 4px 8px var(--shadow-color);
}

.score-label {
  font-size: var(--font-size-xs);
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 0.5px;
  margin-bottom: var(--spacing-xs);
}

.score-value {
  font-size: var(--font-size-xl);
  font-weight: 700;
  color: var(--primary-color);
  font-family: var(--font-family-mono);
}

.game-controls {
  display: flex;
  gap: var(--spacing-sm);
}

/* Buttons */
.control-button,
.overlay-button,
.size-button,
.ai-button {
  padding: 12px 24px;
  border: none;
  border-radius: var(--tile-radius);
  font-size: var(--font-size-base);
  font-weight: 600;
  cursor: pointer;
  transition: all var(--transition-fast);
  position: relative;
  overflow: hidden;
}

.control-button::before,
.overlay-button::before {
  content: '';
  position: absolute;
  top: 50%;
  left: 50%;
  width: 0;
  height: 0;
  background: rgba(255, 255, 255, 0.3);
  border-radius: 50%;
  transform: translate(-50%, -50%);
  transition: width 0.3s ease, height 0.3s ease;
}

.control-button:active::before,
.overlay-button:active::before {
  width: 300px;
  height: 300px;
}

.control-button.primary {
  background: var(--primary-color);
  color: white;
  font-weight: 600;
}

.control-button.primary:hover {
  background: color-mix(in srgb, var(--primary-color) 90%, white);
  transform: translateY(-1px);
}

/* Dark theme primary button fix */
[data-theme="dark"] .control-button.primary {
  background: #ffffff;
  color: #000000;
}

[data-theme="dark"] .control-button.primary:hover {
  background: #f0f0f0;
  color: #000000;
}

.control-button.secondary {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

.control-button.secondary:hover:not(:disabled) {
  background: var(--border-color);
}

.control-button:disabled {
  opacity: 0.5;
  cursor: not-allowed;
  transform: none;
}

/* Game Container */
.game-container {
  position: relative;
  display: flex;
  justify-content: center;
  margin: var(--spacing-xl) 0;
}

.game-board {
  width: var(--board-size);
  height: var(--board-size);
  background: var(--surface-color);
  border-radius: calc(var(--tile-radius) * 2);
  padding: var(--tile-gap);
  box-shadow: 0 8px 16px var(--shadow-color);
  position: relative;
  display: grid;
  grid-template-columns: repeat(4, 1fr);
  grid-template-rows: repeat(4, 1fr);
  gap: var(--tile-gap);
  border: 1px solid var(--border-color);
}

/* Tiles */
.tile {
  width: var(--tile-size);
  height: var(--tile-size);
  border-radius: var(--tile-radius);
  display: flex;
  align-items: center;
  justify-content: center;
  font-weight: 700;
  font-family: var(--font-family-mono);
  position: relative;
  transition: all var(--transition-smooth);
  transform-origin: center;
}

.tile.new-tile {
  animation: tileAppear var(--transition-smooth);
}

.tile.merged-tile {
  animation: tileMerge var(--transition-smooth);
}

@keyframes tileAppear {
  0% {
    transform: scale(0.8);
    opacity: 0;
  }
  60% {
    transform: scale(1.02);
    opacity: 0.8;
  }
  100% {
    transform: scale(1);
    opacity: 1;
  }
}

@keyframes tileMerge {
  0% {
    transform: scale(1);
  }
  40% {
    transform: scale(1.05);
  }
  100% {
    transform: scale(1);
  }
}

/* Tile colors */
.tile[data-value="2"] { background: #eee4da; color: #776e65; }
.tile[data-value="4"] { background: #ede0c8; color: #776e65; }
.tile[data-value="8"] { background: #f2b179; color: #f9f6f2; }
.tile[data-value="16"] { background: #f59563; color: #f9f6f2; }
.tile[data-value="32"] { background: #f67c5f; color: #f9f6f2; }
.tile[data-value="64"] { background: #f65e3b; color: #f9f6f2; }
.tile[data-value="128"] { background: #edcf72; color: #f9f6f2; font-size: 0.9em; }
.tile[data-value="256"] { background: #edcc61; color: #f9f6f2; font-size: 0.9em; }
.tile[data-value="512"] { background: #edc850; color: #f9f6f2; font-size: 0.9em; }
.tile[data-value="1024"] { background: #edc53f; color: #f9f6f2; font-size: 0.8em; }
.tile[data-value="2048"] { background: #edc22e; color: #f9f6f2; font-size: 0.8em; box-shadow: 0 0 20px rgba(237, 194, 46, 0.5); }

/* Higher tiles */
.tile[data-value="4096"] { background: #ff6b6b; color: #f9f6f2; font-size: 0.7em; }
.tile[data-value="8192"] { background: #4ecdc4; color: #f9f6f2; font-size: 0.7em; }

/* Empty tile placeholder */
.tile-placeholder {
  background: rgba(238, 228, 218, 0.35);
  border-radius: var(--tile-radius);
}

/* Dark theme tile placeholders */
[data-theme="dark"] .tile-placeholder {
  background: rgba(255, 255, 255, 0.1);
  border: 1px solid rgba(255, 255, 255, 0.05);
}

/* Dark theme tile colors for better contrast */
[data-theme="dark"] .tile[data-value="2"] { 
  background: #3a3a3a; 
  color: #ffffff; 
}

[data-theme="dark"] .tile[data-value="4"] { 
  background: #4a4a4a; 
  color: #ffffff; 
}

[data-theme="dark"] .tile[data-value="8"] { 
  background: #f2b179; 
  color: #000000; 
}

[data-theme="dark"] .tile[data-value="16"] { 
  background: #f59563; 
  color: #000000; 
}

[data-theme="dark"] .tile[data-value="32"] { 
  background: #f67c5f; 
  color: #ffffff; 
}

[data-theme="dark"] .tile[data-value="64"] { 
  background: #f65e3b; 
  color: #ffffff; 
}

[data-theme="dark"] .tile[data-value="128"] { 
  background: #edcf72; 
  color: #000000; 
  font-size: 0.9em; 
}

[data-theme="dark"] .tile[data-value="256"] { 
  background: #edcc61; 
  color: #000000; 
  font-size: 0.9em; 
}

[data-theme="dark"] .tile[data-value="512"] { 
  background: #edc850; 
  color: #000000; 
  font-size: 0.9em; 
}

[data-theme="dark"] .tile[data-value="1024"] { 
  background: #edc53f; 
  color: #000000; 
  font-size: 0.8em; 
}

[data-theme="dark"] .tile[data-value="2048"] { 
  background: #edc22e; 
  color: #000000; 
  font-size: 0.8em; 
  box-shadow: 0 0 20px rgba(237, 194, 46, 0.7); 
}

[data-theme="dark"] .tile[data-value="4096"] { 
  background: #ff6b6b; 
  color: #ffffff; 
  font-size: 0.7em; 
}

[data-theme="dark"] .tile[data-value="8192"] { 
  background: #4ecdc4; 
  color: #000000; 
  font-size: 0.7em; 
}

/* Dark theme button improvements */
[data-theme="dark"] .control-button.secondary {
  background: var(--dark-surface);
  border-color: var(--dark-border);
  color: var(--dark-text-primary);
}

[data-theme="dark"] .control-button.secondary:hover:not(:disabled) {
  background: var(--dark-border);
  border-color: var(--dark-text-secondary);
}

[data-theme="dark"] .size-button {
  background: var(--dark-surface);
  border-color: var(--dark-border);
  color: var(--dark-text-secondary);
}

[data-theme="dark"] .size-button:hover:not(.active) {
  background: var(--dark-border);
  color: var(--dark-text-primary);
}

[data-theme="dark"] .ai-button {
  background: var(--dark-surface);
  border-color: var(--dark-border);
  color: var(--dark-text-secondary);
}

[data-theme="dark"] .ai-button:hover {
  background: var(--dark-border);
  color: var(--dark-text-primary);
}

[data-theme="dark"] .ai-select {
  background: var(--dark-surface);
  border-color: var(--dark-border);
  color: var(--dark-text-primary);
}

[data-theme="dark"] .nav-button {
  border-color: var(--dark-border);
  color: var(--dark-text-secondary);
}

[data-theme="dark"] .nav-button:hover {
  background: var(--dark-border);
  color: var(--dark-text-primary);
}

/* Dark theme speed button and all variants */
[data-theme="dark"] .speed-button[data-speed="1x"] {
  background: var(--dark-surface);
  color: var(--dark-text-secondary);
  border-color: var(--dark-border);
}

[data-theme="dark"] .speed-button[data-speed="2x"] {
  background: #4caf50;
  color: white;
  border-color: #4caf50;
}

[data-theme="dark"] .speed-button[data-speed="4x"] {
  background: #ff9800;
  color: white;
  border-color: #ff9800;
}

[data-theme="dark"] .speed-button[data-speed="8x"] {
  background: #f44336;
  color: white;
  border-color: #f44336;
}

[data-theme="dark"] .speed-button[data-speed="MAX"] {
  background: linear-gradient(45deg, #e91e63, #9c27b0);
  color: white;
  border-color: transparent;
}

/* Light theme improvements for better contrast */
[data-theme="light"] .tile-placeholder,
:root .tile-placeholder {
  background: rgba(0, 0, 0, 0.08);
  border: 1px solid rgba(0, 0, 0, 0.05);
}

[data-theme="light"] .game-board,
:root .game-board {
  background: #fafafa;
  border: 1px solid #e0e0e0;
}

[data-theme="light"] .control-button.secondary,
:root .control-button.secondary {
  background: #ffffff;
  border: 1px solid #d0d0d0;
  color: #333333;
}

[data-theme="light"] .control-button.secondary:hover:not(:disabled),
:root .control-button.secondary:hover:not(:disabled) {
  background: #f5f5f5;
  border-color: #b0b0b0;
}

/* Dark theme score items */
[data-theme="dark"] .score-item {
  background: var(--dark-surface);
  border-color: var(--dark-border);
}

[data-theme="dark"] .score-value {
  color: var(--dark-text-primary);
}

[data-theme="dark"] .score-label {
  color: var(--dark-text-secondary);
}

/* Dark theme for game options section */
[data-theme="dark"] .game-options {
  background: var(--dark-surface);
  border-color: var(--dark-border);
}

[data-theme="dark"] .option-label {
  color: var(--dark-text-primary);
}

/* Dark theme for overlays */
[data-theme="dark"] .overlay-content {
  background: var(--dark-surface);
  border-color: var(--dark-border);
}

[data-theme="dark"] .overlay-title {
  color: var(--dark-text-primary);
}

[data-theme="dark"] .overlay-message {
  color: var(--dark-text-secondary);
}

[data-theme="dark"] .overlay-button.primary {
  background: #ffffff;
  color: #000000;
}

[data-theme="dark"] .overlay-button.primary:hover {
  background: #f0f0f0;
  color: #000000;
}

[data-theme="dark"] .overlay-button.secondary {
  background: transparent;
  border-color: var(--dark-border);
  color: var(--dark-text-primary);
}

[data-theme="dark"] .overlay-button.secondary:hover {
  background: var(--dark-border);
  color: var(--dark-text-primary);
}

/* Dark theme for header elements */
[data-theme="dark"] .header {
  background: var(--dark-surface);
  border-bottom-color: var(--dark-border);
}

[data-theme="dark"] .title-text {
  color: var(--dark-text-primary);
}

[data-theme="dark"] .title-subtitle {
  color: var(--dark-text-secondary);
}

/* Dark theme for footer */
[data-theme="dark"] .footer {
  background: var(--dark-surface);
  border-top-color: var(--dark-border);
}

[data-theme="dark"] .footer-text {
  color: var(--dark-text-secondary);
}

[data-theme="dark"] .footer-link {
  color: var(--dark-text-primary);
}

[data-theme="dark"] .footer-link:hover {
  color: var(--secondary-color);
}

/* Dark theme for loading screen */
[data-theme="dark"] .loading-screen {
  background: var(--dark-background);
}

[data-theme="dark"] .loading-logo {
  color: var(--dark-text-primary);
}

[data-theme="dark"] .loading-spinner {
  border-color: var(--dark-border);
  border-top-color: var(--secondary-color);
}

[data-theme="dark"] .loading-text {
  color: var(--dark-text-secondary);
}

/* Dark theme for mobile instructions */
[data-theme="dark"] .mobile-instructions {
  color: var(--dark-text-secondary);
}

/* Dark theme for size buttons active state */
[data-theme="dark"] .size-button.active {
  background: #ffffff;
  color: #000000;
  border-color: #ffffff;
}

/* Dark theme for AI button active state */
[data-theme="dark"] .ai-button.active {
  background: var(--secondary-color);
  color: #000000;
  border-color: var(--secondary-color);
}

/* Dark theme for score highlight */
[data-theme="dark"] .score-highlight {
  color: var(--secondary-color);
}

/* Dark theme for skip link accessibility */
[data-theme="dark"] .skip-link {
  background: var(--dark-text-primary);
  color: var(--dark-background);
}

/* Dark theme focus styles */
[data-theme="dark"] button:focus,
[data-theme="dark"] select:focus,
[data-theme="dark"] .nav-button:focus {
  box-shadow: 0 0 0 3px rgba(255, 204, 0, 0.4);
}

/* Dark theme for game overlay backdrop */
[data-theme="dark"] .game-overlay {
  background: rgba(0, 0, 0, 0.9);
}

/* Game Overlays */
.game-overlay {
  position: absolute;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: rgba(0, 0, 0, 0.8);
  display: flex;
  align-items: center;
  justify-content: center;
  border-radius: calc(var(--tile-radius) * 2);
  z-index: var(--z-modal);
  backdrop-filter: blur(4px);
  transition: all var(--transition-base);
}

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

.overlay-content {
  background: var(--surface-color);
  padding: var(--spacing-2xl);
  border-radius: calc(var(--tile-radius) * 2);
  text-align: center;
  box-shadow: 0 20px 40px var(--shadow-color);
  transform: scale(0.9);
  transition: transform var(--transition-smooth);
  border: 1px solid var(--border-color);
}

.game-overlay:not(.hidden) .overlay-content {
  transform: scale(1);
}

.overlay-title {
  margin: 0 0 var(--spacing-md);
  font-size: var(--font-size-3xl);
  color: var(--primary-color);
}

.overlay-message {
  margin: 0 0 var(--spacing-lg);
  color: var(--text-secondary);
}

.overlay-score {
  margin: var(--spacing-lg) 0;
  font-size: var(--font-size-xl);
}

.score-highlight {
  color: var(--secondary-color);
  font-weight: 700;
  font-family: var(--font-family-mono);
}

.overlay-actions {
  display: flex;
  gap: var(--spacing-md);
  justify-content: center;
}

.overlay-button.primary {
  background: var(--primary-color);
  color: white;
}

.overlay-button.secondary {
  background: transparent;
  border: 1px solid var(--border-color);
  color: var(--text-primary);
}

/* Game Options */
.game-options {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  border-radius: calc(var(--tile-radius) * 2);
  padding: var(--spacing-xl);
  margin: var(--spacing-xl) 0;
  box-shadow: 0 4px 8px var(--shadow-color);
}

.option-group {
  margin-bottom: var(--spacing-lg);
}

.option-group:last-child {
  margin-bottom: 0;
}

.option-label {
  display: block;
  font-weight: 600;
  margin-bottom: var(--spacing-sm);
  color: var(--text-primary);
}

.size-buttons {
  display: flex;
  gap: var(--spacing-sm);
  flex-wrap: wrap;
}

.size-button {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  min-width: 60px;
}

.size-button.active {
  background: var(--primary-color);
  color: white;
  border-color: var(--primary-color);
}

.size-button:hover:not(.active) {
  background: var(--border-color);
}

.ai-controls {
  display: flex;
  gap: var(--spacing-sm);
  align-items: center;
  flex-wrap: wrap;
}

.ai-button {
  background: var(--surface-color);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
}

.ai-button:hover {
  background: var(--border-color);
}

.ai-button.active {
  background: var(--secondary-color);
  color: var(--primary-color);
  border-color: var(--secondary-color);
}

.speed-button {
  min-width: 50px;
  font-family: var(--font-family-mono);
  font-weight: 600;
  position: relative;
}

.speed-button[data-speed="1x"] {
  background: var(--surface-color);
  color: var(--text-secondary);
}

.speed-button[data-speed="2x"] {
  background: #4caf50;
  color: white;
}

.speed-button[data-speed="4x"] {
  background: #ff9800;
  color: white;
}

.speed-button[data-speed="8x"] {
  background: #f44336;
  color: white;
}

.speed-button[data-speed="MAX"] {
  background: linear-gradient(45deg, #e91e63, #9c27b0);
  color: white;
  animation: pulse-speed 1s ease-in-out infinite alternate;
}

@keyframes pulse-speed {
  0% { transform: scale(1); }
  100% { transform: scale(1.05); }
}

.ai-select {
  padding: 8px 12px;
  border: 1px solid var(--border-color);
  border-radius: var(--tile-radius);
  background: var(--surface-color);
  color: var(--text-primary);
  font-size: var(--font-size-sm);
  cursor: pointer;
}

.ai-select:focus {
  outline: none;
  border-color: var(--secondary-color);
  box-shadow: 0 0 0 3px rgba(255, 204, 0, 0.1);
}

/* Instructions */
.mobile-instructions {
  text-align: center;
  margin: var(--spacing-xl) 0;
  color: var(--text-secondary);
}

.instruction-text {
  font-size: var(--font-size-sm);
  line-height: 1.5;
  max-width: 600px;
  margin: 0 auto;
}

.desktop-only {
  display: inline;
}

.mobile-only {
  display: none;
}

/* Footer */
.footer {
  background: var(--surface-color);
  border-top: 1px solid var(--border-color);
  margin-top: auto;
  padding: var(--spacing-lg) 0;
}

.footer-text {
  text-align: center;
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
  margin: 0;
}

.footer-link {
  color: var(--primary-color);
  text-decoration: none;
  margin: 0 var(--spacing-xs);
}

.footer-link:hover {
  text-decoration: underline;
}

/* Loading Screen */
.loading-screen {
  position: fixed;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background: var(--background-color);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: var(--z-modal);
  transition: opacity var(--transition-base);
}

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

.loading-content {
  text-align: center;
}

.loading-logo {
  font-size: var(--font-size-4xl);
  font-weight: 700;
  color: var(--primary-color);
  margin-bottom: var(--spacing-md);
  font-family: var(--font-family-mono);
}

.loading-spinner {
  width: 40px;
  height: 40px;
  border: 4px solid var(--border-color);
  border-top: 4px solid var(--secondary-color);
  border-radius: 50%;
  animation: spin 1s linear infinite;
  margin: 0 auto var(--spacing-md);
}

@keyframes spin {
  0% { transform: rotate(0deg); }
  100% { transform: rotate(360deg); }
}

.loading-text {
  color: var(--text-secondary);
  font-size: var(--font-size-sm);
}

/* Responsive Design */
@media (max-width: 768px) {
  :root {
    --board-size: min(350px, 90vw);
    --spacing-md: 0.75rem;
    --spacing-lg: 1rem;
    --spacing-xl: 1.5rem;
  }
  
  .header .container {
    padding: var(--spacing-sm) var(--spacing-md);
  }
  
  .game-title {
    font-size: var(--font-size-xl);
  }
  
  .game-info {
    flex-direction: column;
    align-items: stretch;
    gap: var(--spacing-md);
  }
  
  .score-panel {
    justify-content: center;
  }
  
  .game-controls {
    justify-content: center;
  }
  
  .size-buttons,
  .ai-controls {
    justify-content: center;
  }
  
  .overlay-actions {
    flex-direction: column;
  }
  
  .desktop-only {
    display: none;
  }
  
  .mobile-only {
    display: inline;
  }
  
  .nav-button {
    width: 36px;
    height: 36px;
  }
}

@media (max-width: 480px) {
  :root {
    --board-size: min(300px, 85vw);
  }
  
  .container {
    padding: 0 var(--spacing-sm);
  }
  
  .score-item {
    min-width: 60px;
    padding: var(--spacing-sm);
  }
  
  .score-value {
    font-size: var(--font-size-lg);
  }
  
  .control-button {
    padding: 8px 16px;
    font-size: var(--font-size-sm);
  }
}

/* Board size variations */
.board-size-3 {
  --board-size: min(300px, 90vw);
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
}

.board-size-5 {
  --board-size: min(450px, 90vw);
  grid-template-columns: repeat(5, 1fr);
  grid-template-rows: repeat(5, 1fr);
}

.board-size-6 {
  --board-size: min(500px, 90vw);
  grid-template-columns: repeat(6, 1fr);
  grid-template-rows: repeat(6, 1fr);
}

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

/* Automatic dark mode based on system preference */
@media (prefers-color-scheme: dark) {
  :root:not([data-theme]) {
    --primary-color: var(--dark-primary);
    --background-color: var(--dark-background);
    --surface-color: var(--dark-surface);
    --text-primary: var(--dark-text-primary);
    --text-secondary: var(--dark-text-secondary);
    --border-color: var(--dark-border);
    --shadow-color: var(--dark-shadow);
  }
  
  /* Apply all dark theme styles when system prefers dark */
  :root:not([data-theme]) .tile-placeholder {
    background: rgba(255, 255, 255, 0.1);
    border: 1px solid rgba(255, 255, 255, 0.05);
  }
  
  :root:not([data-theme]) .control-button.primary {
    background: #ffffff;
    color: #000000;
  }
  
  :root:not([data-theme]) .control-button.primary:hover {
    background: #f0f0f0;
    color: #000000;
  }
  
  :root:not([data-theme]) .control-button.secondary {
    background: var(--dark-surface);
    border-color: var(--dark-border);
    color: var(--dark-text-primary);
  }
  
  :root:not([data-theme]) .control-button.secondary:hover:not(:disabled) {
    background: var(--dark-border);
    border-color: var(--dark-text-secondary);
  }
}

/* Focus styles for accessibility */
button:focus,
select:focus,
.nav-button:focus {
  outline: none;
  box-shadow: 0 0 0 3px rgba(255, 204, 0, 0.3);
}

/* High contrast mode support */
@media (prefers-contrast: high) {
  :root {
    --border-color: #000000;
    --shadow-color: rgba(0, 0, 0, 0.5);
  }
  
  .tile {
    border: 2px solid #000000;
  }
}