body { margin:0; overflow:hidden; background:black; }
#ui {
  position: fixed;
  top: 10px;
  left: 10px;
}
button {
  background: #00ffff;
  color: black;
  border: none;
  padding: 10px;
  margin: 5px;
  font-weight: bold;
  box-shadow: 0 0 15px #00ffff;
}