html {
  height: 100%;
  width: 100%;
}

body {
  height: 100%;
  width: 100%;
  background-color: #ccc;
  margin: 0;
  display: flex;
  justify-content: center;
  align-items: center;

  /* leave it to hide the scrollbars */
  overflow: hidden;
}

canvas {
  display: block;
  --w: min(100vh, 100vw);
  margin: auto;
  height: var(--w) !important;
  width: var(--w) !important;
}