html,body {
  margin: 0;
  position: relative;
  min-height: 100vh;
 /* background-color: aqua;*/
}
canvas {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translate(-50%, -50%);
  max-width: 100%;
  max-height: 100%;
  object-fit: scale-down;
  /*box-shadow: 0 10px 20px rgba(0,0,0,0.19), 0 6px 6px rgba(0,0,0,0.23);*/
  filter: drop-shadow(0.3rem 0.3rem 0.3rem rgba(0,0,0,0.43));
}