body { margin:0; overflow:hidden; background:#000; font-family:sans-serif; }

#ui {
  position:absolute;
  top:10px;
  left:10px;
  color:white;
}

#devMenu {
  position:absolute;
  right:10px;
  top:60px;
  width:250px;
  background:rgba(0,0,0,0.85);
  color:white;
  display:none;
  padding:10px;
}
button { margin:2px; }