pre {
  overflow: scroll;
  max-width: 50em;
}

div.sidenote {
  max-width: 20em;
  float: right;
  border-width: 1px;
  border-style: solid;
  border-color: #880;
  background-color: #FF8;
  clear: right;
  margin: 1em;
  padding: 1em;
}