html, body {
  padding: 0px;
  margin: 0px;
  width: 100%;
  height: 100%;
  overflow: hidden;
}


canvas.fullscreen {
  width: 100vw;
  height: 100vh;
}

#ui {
  position: absolute;
  right: 10px;
  top: 10px;
  width: 10em;
  height: 5em;
  background-color: aliceblue;
}