body {
  /* leave it to hide the scrollbars */
  overflow: hidden;
  margin: 0;
  display: flex;
  justify-content: center; 
  align-items: center; 
}

canvas {
  margin: 0;
  position: absolute;
  top: 50%;
  left: 50%;
  -ms-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}