.reveal section img.nobg {
  background: transparent;
  box-shadow: none;
  border: 0;
}

.reveal section img.whiteborder {
  background: white;
  padding: 1em;
  border: 0;
}

.reveal pre code {
  font-size: 130%;
  padding: 1em;
  line-height: 1.2;
}