:root {
  color-scheme: light dark;
  font-family: monospace;
}

html, body {
  margin: 0;
  height: 100%;
}

canvas {
  width: 100%;
  height: 100%;
  display: block;
}

#b {
  position: absolute;
  text-align: center;
  width: 100%;
  top: 1em;
  left: 0;
}

#fail {
  position: absolute;
  top: 0;
  left: 0;
  width: 100%;
  height: 100%;
  display: flex;
  justify-content: center;
  align-items: center;
  color: red;
}