html,
body {
  margin: 0;
  padding: 0;
  background: black;
  height: 100%;
  width: 100%;
  overflow: hidden;
  display: flex;
  align-items: center;
  justify-content: center;
}

body.pointer {
  cursor: pointer;
}

canvas {
  position: absolute;
  top: 0;
  left: 0;
  display: block;
}

#canvas-container {
  position: relative;
  width: 640px;
  height: 360px;
}