body,
html {
  margin: 0;
  padding: 0;
  width: 100vw;
  height: 100vh;
  display: block;
  overflow: hidden;
  background-color: #233;
}
canvas {
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  margin: auto;
  overflow: auto;
  position: fixed;
  max-width: 100%;
  max-height: 100%;
  object-fit: contain;
}