.reveal .text-bg {
  background-color: rgba(0, 0, 0, 0.8);
  color: #fff;
  padding: 1em;
  padding-bottom: 3em;
}

.reveal .photo-credit {
  position: absolute;
  font-size: small;
  bottom: 1em;
  color: #aaa;
}

.reveal .text-bg {
  background-color: rgba(0, 0, 0, 0.8);
  color: #fff;
  padding: 1em;
  padding-bottom: 2em;
}

.reveal .photo-credit {
  position: absolute;
  font-size: x-small;
  bottom: 1em;
  color: #888;
}

.reveal .photo-credit a {
  color: #ccc;
}

Adjust text and link color in photo credit.
Adjust text and link color in photo credit.
