html {
  font-family: sans-serif;    
}

#display {
  font-size: 200px;
  color: blue;
}

#buttons button {
  font-size: 40px;
  min-width: 200px;
  color: white;
  background-color: navy;
  border: none;
  border-radius: 8px;
  padding: 10px;
}


#display, #buttons {
  /* pablo */
  text-align: center;
}