html, body {
  background: radial-gradient(#0d0d0d, #161718);
  /* background: rgb(0, 0, 0); */
  display: flex;
  width: 100%;
  height: 100%;
  align-items: center;
  justify-content: center;
  margin: 0;
  padding: 0;
  overflow: hidden;
  position: fixed;
}

/* Grey square always present behind canvas */
body::before {
  content: '';
  position: absolute;
  width: min(100vw, 100vh);
  height: min(100vw, 100vh);
  background-color: #333;
  z-index: 0;
}

canvas {
  margin:0;
  padding:0;
  display: block;
  position: relative;
  z-index: 1;
  transition: opacity 0.1s ease-out;
}

/* Hide canvas during resize to show grey square */
canvas.resizing {
  opacity: 0;
}