html,
body {
  margin: 0;
  height: 100%;
  overflow: hidden;
  background: #1c120c; /* palette brown-black */
  touch-action: none;  /* no tap-scrolling or zooming anywhere on the page */
  -webkit-touch-callout: none; /* no long-press menu while holding jump */
  user-select: none;
  -webkit-user-select: none;
  -webkit-tap-highlight-color: transparent;
}

body {
  display: flex;
  align-items: center;
  justify-content: center;
}

/* Scale the 960x540 canvas to fit the window, keeping 16:9.
   The leftover space shows as letterbox bars in the palette brown-black. */
#game {
  display: block;
  width: min(100vw, calc(100vh * 16 / 9));
  height: min(100vh, calc(100vw * 9 / 16));
  background: #1c120c;
}