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

#container {
  padding: 0;
  margin: 0;
  position: absolute;
  width: 100%;
  height: 100%;
  background-color: black;
}

button{
  position: absolute;
  top: 1rem;
  left: 1rem;
  color: white;
  background: gray;
  boder: 0 solid white;
  padding: 1rem;
  font-size: 1.1rem;
}