.main {
  font-family: arial;
  padding: 25px;
  margin-top: 40px;
  font-size: 4.0em;
}

#output {
  font-size: 8.0em;
  width: 43%;
  height: auto;
  background-color: white;
  border: 3px solid black;
  margin-right: auto;
  margin-left: auto;
  margin-top: 45px;
}

.btn {
  margin-top: 40px;
  font-size: 1.8em;
}

.article {
  padding:8% 20% 2%;
}