:root {
  --bg-primary: #1c1e21;
  --bg-secondary: #242629;
  --bg-tertiary: #2c2f33;
  --bg-card: #2a2d31;
  --text-primary: #ffffff;
  --text-secondary: #e4e6eb;
  --text-muted: #b0b3b8;
  --accent-primary: #00d4ff;
  --accent-secondary: #00ff88;
  --accent-warm: #ff9f43;
  --danger: #ff4466;
  --focus-ring: #00d4ff;
  --focus-glow: rgba(0, 212, 255, 0.4);
  --radius-sm: 8px;
  --radius-md: 12px;
  --radius-lg: 16px;
}

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

body {
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', sans-serif;
  background: var(--bg-primary);
  color: var(--text-primary);
  width: 600px;
  height: 600px;
  overflow: hidden;
}

#app {
  width: 100%;
  height: 100%;
  position: relative;
}

/* --- Screens --- */
.screen {
  width: 100%;
  height: 100%;
  display: flex;
  flex-direction: column;
  position: absolute;
  top: 0;
  left: 0;
}
.screen.hidden { display: none; }

/* --- Header --- */
.header {
  display: flex;
  align-items: center;
  padding: 16px 20px;
  background: var(--bg-secondary);
  gap: 12px;
  flex-shrink: 0;
}
.header h1 {
  font-size: 28px;
  font-weight: 700;
  flex: 1;
}
.header-meta {
  font-size: 16px;
  font-weight: 600;
  color: var(--accent-warm);
}
.back-btn {
  background: transparent;
  color: var(--text-primary);
  font-size: 24px;
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  border: 2px solid transparent;
}

/* --- Content Area --- */
.content {
  flex: 1;
  padding: 16px 20px;
  display: flex;
  flex-direction: column;
  gap: 16px;
}

/* --- Menu --- */
.menu-content {
  justify-content: center;
  align-items: center;
  gap: 40px;
}
.menu-tagline {
  font-size: 20px;
  color: var(--text-secondary);
  text-align: center;
  max-width: 420px;
  line-height: 1.4;
}
.menu-actions {
  display: flex;
  flex-direction: column;
  gap: 16px;
  width: 320px;
}

/* --- How To Play --- */
.howto-content {
  justify-content: center;
  gap: 14px;
}
.howto-row {
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 12px 20px;
  background: var(--bg-card);
  border-radius: var(--radius-md);
}
.howto-key {
  font-size: 20px;
  font-weight: 700;
  color: var(--accent-primary);
  width: 96px;
  flex-shrink: 0;
  text-align: center;
}
.howto-desc {
  font-size: 18px;
  color: var(--text-secondary);
}
.howto-note {
  font-size: 15px;
  color: var(--text-muted);
  text-align: center;
  margin-top: 8px;
  line-height: 1.4;
}

/* --- Navigation Bar --- */
.nav-bar {
  display: flex;
  gap: 8px;
  padding: 12px 20px;
  background: var(--bg-secondary);
  flex-shrink: 0;
}
.nav-item {
  flex: 1;
  padding: 16px 16px;
  background: var(--bg-tertiary);
  border-radius: var(--radius-md);
  color: var(--text-primary);
  font-size: 18px;
  font-weight: 600;
  text-align: center;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
}
.nav-item.primary {
  background: var(--accent-primary);
  color: var(--bg-primary);
}
.nav-item.primary:focus { background: #33ddff; }
.nav-item.danger {
  background: var(--danger);
  color: #ffffff;
}

/* --- Focus States --- */
.focusable {
  transition: transform 0.12s ease, box-shadow 0.12s ease, border-color 0.12s ease, background 0.12s ease;
  border: 2px solid transparent;
  cursor: pointer;
  min-height: 44px;
}
.focusable:focus {
  outline: none;
  border-color: var(--focus-ring);
  box-shadow: 0 0 20px var(--focus-glow);
}

/* --- Game Layout --- */
.game-layout {
  flex: 1;
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 24px;
  padding: 20px;
}
.board-wrap {
  flex-shrink: 0;
}
#board {
  background: var(--bg-secondary);
  border-radius: var(--radius-md);
  border: 2px solid var(--bg-tertiary);
  display: block;
}

/* --- Side Panel --- */
.side-panel {
  width: 230px;
  display: flex;
  flex-direction: column;
  gap: 14px;
}
.stat {
  background: var(--bg-card);
  border-radius: var(--radius-md);
  padding: 12px 16px;
}
.stat-grid {
  display: grid;
  grid-template-columns: 1fr 1fr;
  gap: 14px;
}
.stat-label {
  font-size: 14px;
  font-weight: 600;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
}
.stat-value {
  font-size: 34px;
  font-weight: 800;
  color: var(--accent-secondary);
  line-height: 1.1;
  margin-top: 4px;
}
.stat-value.small {
  font-size: 26px;
}
.next-box {
  background: var(--bg-card);
  border-radius: var(--radius-md);
  padding: 12px 16px;
  display: flex;
  flex-direction: column;
  align-items: flex-start;
  gap: 8px;
}
#next {
  display: block;
  margin: 0 auto;
}
.best-line {
  font-size: 16px;
  font-weight: 600;
  color: var(--accent-warm);
  text-align: center;
}

/* --- Overlays --- */
.overlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  background: rgba(28, 30, 33, 0.94);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 50;
}
.overlay.hidden { display: none; }

.overlay-content {
  display: flex;
  flex-direction: column;
  align-items: center;
  gap: 16px;
  padding: 40px;
}
.overlay-title {
  font-size: 40px;
  font-weight: 800;
  color: var(--accent-primary);
  text-transform: uppercase;
  letter-spacing: 4px;
  margin-bottom: 8px;
}
.overlay-title.danger { color: var(--danger); }

.final-score {
  font-size: 64px;
  font-weight: 800;
  color: var(--accent-secondary);
  line-height: 1;
}
.final-label {
  font-size: 16px;
  color: var(--text-secondary);
}
.final-best {
  font-size: 16px;
  font-weight: 600;
  color: var(--accent-warm);
  margin-bottom: 12px;
}
.overlay-btn {
  width: 260px;
}

/* --- Utility --- */
.hidden { display: none !important; }