body {
  font: 1em sans-serif;
  color: #333;
}

label {
  display: block;
  padding: 10px 0;
}

input {
  font: inherit;
  text-align: right;
  padding: 10px;
  border: 1px solid #aaa;
  border-radius: 0.25em;
}

output {
  display: block;
  padding: 10px 5px;
  font-weight: bold;
  color: #009;
  border: 1px solid #ddd;
  border-radius: 0.25em;
  line-height: 2;
}

output.prime {
  color: #090;
}

#article {
  padding: 10% 10% 5% 0px;
}