body {
  background-color: lime; 
}
h1 {
  color: cyan;
  font-family: Lobster;
  text-align: center;
}
#result {
  background-color: white;
}

#container {
  position: fixed;
  top: 50%; 
  left: 50%;
  transform: translate(-50%, -50%);
  background-color: darkgreen;
  border-radius: 2em;
  padding: 20px;
}