body {
  margin: 0;
  padding: 0;
  border: 0;
  height: 100vh;
  width: 100vw;
}

canvas {
  height: 100%;
  width: 100%;
  position: absolute;
  z-index: 0;
}

#overlay-canvas {
  z-index: 1;
  cursor: crosshair;
}

button {
  position: relative;
  z-index: 2;
  font-size: 18px;
}