html, body {
  margin: 0;
  height: 100%;
  background: #000;
  display: flex;
  align-items: center;
  justify-content: center;
  overflow: hidden;
}

canvas#screen {
  /* 320 x 200 at 4x = 1280 x 800 */
  width: 1280px;
  height: 800px;
  display: block;

  /* Keep the framebuffer pixels crisp, no smoothing */
  image-rendering: pixelated;
  image-rendering: crisp-edges;
  image-rendering: -moz-crisp-edges;

  /* We handle cursor drawing in the framebuffer; hide the OS pointer */
  cursor: none;
}

/* If the window is smaller than 1280x800, scale down while preserving aspect. */
@media (max-width: 1280px) or (max-height: 800px) {
  canvas#screen {
    width: min(100vw, calc(100vh * 320 / 200));
    height: auto;
    aspect-ratio: 320 / 250;
  }
}