body {
  margin: 0;
  background: #111;
  color: #fff;
  font-family: sans-serif;
}

canvas {
  display: block;
}

#tooltip {
  position: absolute;
  background: rgba(255, 255, 255, 0.9);
  color: #000;
  padding: 4px 8px;
  border-radius: 4px;
  font-size: 14px;
  pointer-events: none;
  display: none;
  z-index: 10;
}