:root {
  --bg: #0f172a;
  --panel: #1e293b;
  --accent: #22c55e;
  --accent-dark: #16a34a;
  --text: #e2e8f0;
  --muted: #94a3b8;
  --danger: #ef4444;
}

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

body {
  font-family: 'Segoe UI', Tahoma, sans-serif;
  background: radial-gradient(circle at top, #1e293b, var(--bg));
  color: var(--text);
  min-height: 100vh;
  display: flex;
  align-items: center;
  justify-content: center;
  padding: 20px;
}

.game-wrapper {
  width: 100%;
  max-width: 440px;
}

.game-header {
  display: flex;
  align-items: center;
  justify-content: space-between;
  margin-bottom: 16px;
}

.game-header h1 {
  font-size: 2rem;
}

.scoreboard {
  display: flex;
  gap: 12px;
}

.score-box {
  background: var(--panel);
  border-radius: 12px;
  padding: 8px 16px;
  text-align: center;
  min-width: 78px;
}

.score-box .label {
  display: block;
  font-size: 0.72rem;
  color: var(--muted);
  text-transform: uppercase;
  letter-spacing: 0.05em;
}

.score-box span:last-child {
  font-size: 1.4rem;
  font-weight: 700;
  color: var(--accent);
}

.board-container {
  position: relative;
  width: 100%;
  aspect-ratio: 1 / 1;
}

canvas {
  width: 100%;
  height: 100%;
  background: var(--panel);
  border-radius: 16px;
  box-shadow: 0 20px 45px rgba(0, 0, 0, 0.45);
  display: block;
}

.overlay {
  position: absolute;
  inset: 0;
  background: rgba(15, 23, 42, 0.88);
  border-radius: 16px;
  display: flex;
  align-items: center;
  justify-content: center;
  text-align: center;
  transition: opacity 0.25s ease;
}

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

.overlay-content h2 {
  font-size: 1.6rem;
  margin-bottom: 8px;
}

.overlay-content p {
  color: var(--muted);
  margin-bottom: 18px;
  padding: 0 20px;
}

.btn {
  background: var(--accent);
  color: #06210f;
  border: none;
  padding: 12px 28px;
  font-size: 1rem;
  font-weight: 700;
  border-radius: 10px;
  cursor: pointer;
  transition: background 0.2s ease, transform 0.1s ease;
}

.btn:hover {
  background: var(--accent-dark);
}

.btn:active {
  transform: scale(0.97);
}

.btn:disabled {
  opacity: 0.5;
  cursor: not-allowed;
}

.btn.ghost {
  background: transparent;
  color: var(--text);
  border: 1px solid var(--muted);
}

.btn.ghost:hover:not(:disabled) {
  border-color: var(--accent);
  color: var(--accent);
}

.controls {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 16px;
  margin-top: 16px;
}

.speed {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.85rem;
  color: var(--muted);
}

.speed input {
  accent-color: var(--accent);
}

.hint {
  text-align: center;
  margin-top: 14px;
  font-size: 0.8rem;
  color: var(--muted);
}