:root {
  --bg-primary: #0D1117;
  --bg-secondary: #161B22;
  --bg-tertiary: #21262D;
  --text-primary: #F0F6FC;
  --text-secondary: #8B949E;
  --text-muted: #484F58;
  --accent: #3B82F6;
  --border: #30363D;
  --btn-bg: #21262D;
  --btn-active: #30363D;
  --overlay-bg: rgba(0, 0, 0, 0.85);
  --board-bg: #0A0E14;
}

@media (prefers-color-scheme: light) {
  :root {
    --bg-primary: #FFFFFF;
    --bg-secondary: #F6F8FA;
    --bg-tertiary: #E9ECF0;
    --text-primary: #1B1E28;
    --text-secondary: #57606A;
    --text-muted: #8C959F;
    --accent: #3182F6;
    --border: #D0D7DE;
    --btn-bg: #E9ECF0;
    --btn-active: #D0D7DE;
    --overlay-bg: rgba(255, 255, 255, 0.9);
    --board-bg: #F0F2F5;
  }
}

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

html, body {
  height: 100%;
  width: 100%;
}

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Pretendard', 'Segoe UI', Roboto, sans-serif;
  background-color: var(--bg-primary);
  color: var(--text-primary);
  display: flex;
  justify-content: center;
  align-items: center;
  min-height: 100dvh;
  overflow: hidden;
  user-select: none;
  -webkit-user-select: none;
}

#app {
  position: relative;
  width: 100%;
  max-width: 480px;
  height: 100dvh;
  display: flex;
  flex-direction: column;
  background-color: var(--bg-secondary);
  overflow: hidden;
}

/* Header */
#header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 12px 16px;
  background-color: var(--bg-secondary);
  border-bottom: 1px solid var(--border);
  flex-shrink: 0;
  z-index: 10;
}

#header-title {
  font-size: 18px;
  font-weight: 700;
  background: linear-gradient(90deg, #3B82F6, #8B5CF6, #EC4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 2px;
}

#score-display {
  display: flex;
  align-items: center;
  gap: 12px;
  font-size: 22px;
  font-weight: 700;
  color: var(--text-primary);
  font-variant-numeric: tabular-nums;
}

#score-display .score-separator {
  color: var(--text-muted);
  font-size: 18px;
}

#score-display .player-label {
  font-size: 11px;
  font-weight: 500;
  color: var(--text-secondary);
  text-align: center;
  letter-spacing: 0.5px;
}

.score-block {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 2px;
}

/* Canvas area */
#canvas-container {
  flex: 1;
  position: relative;
  display: flex;
  align-items: center;
  justify-content: center;
  background-color: var(--board-bg);
  overflow: hidden;
}

#gameCanvas {
  display: block;
  touch-action: none;
}

/* Overlay screens */
.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background-color: var(--overlay-bg);
  backdrop-filter: blur(8px);
  -webkit-backdrop-filter: blur(8px);
  z-index: 50;
  padding: 24px;
  gap: 20px;
  transition: opacity 0.25s ease;
}

.overlay.hidden {
  display: none;
}

/* Start screen */
#start-screen .game-title {
  font-size: 64px;
  font-weight: 900;
  background: linear-gradient(135deg, #3B82F6, #8B5CF6, #EC4899);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: 8px;
  margin-bottom: 4px;
  text-align: center;
}

#start-screen .game-subtitle {
  font-size: 13px;
  color: var(--text-secondary);
  letter-spacing: 1px;
  margin-bottom: 8px;
  text-align: center;
}

/* Difficulty selector */
.difficulty-section {
  width: 100%;
  max-width: 280px;
}

.difficulty-label {
  font-size: 12px;
  font-weight: 600;
  color: var(--text-secondary);
  text-transform: uppercase;
  letter-spacing: 1px;
  margin-bottom: 10px;
  text-align: center;
}

.difficulty-buttons {
  display: flex;
  gap: 8px;
  width: 100%;
}

.diff-btn {
  flex: 1;
  padding: 10px 6px;
  border: 1px solid var(--border);
  border-radius: 8px;
  background-color: var(--btn-bg);
  color: var(--text-secondary);
  font-size: 13px;
  font-weight: 600;
  cursor: pointer;
  transition: all 0.15s ease;
  font-family: inherit;
  text-align: center;
}

.diff-btn:hover {
  border-color: var(--accent);
  color: var(--text-primary);
}

.diff-btn.active {
  background-color: var(--accent);
  border-color: var(--accent);
  color: #ffffff;
}

/* Buttons */
.btn-primary {
  padding: 14px 40px;
  background: linear-gradient(135deg, #3B82F6, #8B5CF6);
  border: none;
  border-radius: 12px;
  color: #ffffff;
  font-size: 16px;
  font-weight: 700;
  cursor: pointer;
  font-family: inherit;
  letter-spacing: 1px;
  transition: all 0.15s ease;
  min-width: 200px;
  text-align: center;
}

.btn-primary:hover {
  transform: translateY(-1px);
  box-shadow: 0 6px 20px rgba(59, 130, 246, 0.4);
}

.btn-primary:active {
  transform: translateY(0);
}

.btn-secondary {
  padding: 10px 24px;
  background-color: var(--btn-bg);
  border: 1px solid var(--border);
  border-radius: 10px;
  color: var(--text-primary);
  font-size: 14px;
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.15s ease;
  min-width: 140px;
  text-align: center;
}

.btn-secondary:hover {
  background-color: var(--btn-active);
  border-color: var(--accent);
}

/* Game over screen */
#gameover-screen .result-title {
  font-size: 36px;
  font-weight: 900;
  text-align: center;
  letter-spacing: 2px;
}

#gameover-screen .result-title.win {
  background: linear-gradient(135deg, #3B82F6, #8B5CF6);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

#gameover-screen .result-title.lose {
  background: linear-gradient(135deg, #EC4899, #EF4444);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}

#gameover-screen .final-score {
  font-size: 48px;
  font-weight: 700;
  color: var(--text-primary);
  letter-spacing: 4px;
  font-variant-numeric: tabular-nums;
}

#gameover-screen .result-subtitle {
  font-size: 13px;
  color: var(--text-secondary);
  text-align: center;
  letter-spacing: 0.5px;
}

.gameover-buttons {
  display: flex;
  flex-direction: column;
  gap: 10px;
  width: 100%;
  max-width: 240px;
}

/* Pause screen */
#pause-screen .pause-title {
  font-size: 32px;
  font-weight: 800;
  color: var(--text-primary);
  letter-spacing: 4px;
}

#pause-screen .pause-hint {
  font-size: 13px;
  color: var(--text-secondary);
  text-align: center;
}

/* Controls hint */
#controls-hint {
  flex-shrink: 0;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 8px 16px;
  background-color: var(--bg-secondary);
  border-top: 1px solid var(--border);
}

#controls-hint .hint-text {
  font-size: 11px;
  color: var(--text-muted);
  letter-spacing: 0.3px;
}

#pause-btn {
  padding: 6px 14px;
  background-color: var(--btn-bg);
  border: 1px solid var(--border);
  border-radius: 6px;
  color: var(--text-secondary);
  font-size: 12px;
  font-weight: 600;
  cursor: pointer;
  font-family: inherit;
  transition: all 0.15s ease;
}

#pause-btn:hover {
  background-color: var(--btn-active);
  color: var(--text-primary);
}

/* Best score badge */
.best-badge {
  font-size: 12px;
  color: var(--text-secondary);
  background-color: var(--bg-tertiary);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 4px 12px;
}

.best-badge span {
  color: var(--accent);
  font-weight: 700;
}

/* Responsive tweaks for very small screens */
@media (max-height: 600px) {
  #start-screen .game-title {
    font-size: 48px;
  }
  .overlay {
    gap: 14px;
  }
}