body {
  margin: 4em;
  font-family: 'Georgia', serif;
  max-width: 60em;
  margin-left: auto;
  margin-right: auto;
}
.hidden {
  display: none;
}
.disable {
  color: grey!important;
  cursor: not-allowed!important;
}
.footer {
  text-align: center;
  border-top: 1px solid #ccc;
  padding: 1em;
  margin: 2em;
}