html, body {
  margin: 0;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  width: 100%;
  height: 100%;
}

canvas {
  position: absolute;
  left: 50%;
  top: 50%; 
  transform: translate(-50%, -50%);
  max-width: 100%;
  max-height: 100%;
  object-fit: scale-down;
  z-index: 1;
}