html, body {
  padding: 0;
  min-height: 100vh;
  background-image: url("https://assets.codepen.io/1082534/tXtwrPd.jpeg");
  background-position: center center;
  background-size: cover;
}

canvas {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  touch-action: none;
}