#display{
  display: block;
  text-align: center;
  font-size: 10em;
  font-family: monospace;
}

.container{
  text-align: center;
}

button{
  width: 50px;
  height: 50px;
  font-family: Arial, Sans-Serif;
  margin: 10px;
  font-size: 3em;
  color: white;
  background-color: dodgerblue;
  border-radius: 25px;
  border: none;
  cursor: pointer;
  font-weight: bold;
}