body {
  margin: 0;
  background-color: #000;
  color: #fff;
  font-family: sans-serif;
  display: flex;
  justify-content: center;
  align-items: center;
  height: 100vh;
}

#loading, #startButton {
  position: absolute;
}

#gameCanvas {
  display: none;
  background-color: #111;
}