reveal.css

  background-image: url(data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAACAAAAAgCAYAAABzenr0AAAAcElEQVRYR+2WSQoAIQwEzf8f7XiOMkUQxUPlGkM3hVmiQfQR9GYnH1SsAQlI4DiBqkCMoNb9y2e90IAEJPAcgdznU9+engMaeJ7Azh5Y1U67gAho4DqBqmB1buAf0MB1AlVBek83ZPkmJMGc1wAR+AAqod/B97TRpQAAAABJRU5ErkJggg==); }

.reveal .overlay .viewport {
  position: absolute;
  top: 40px;
  right: 0;
  bottom: 0;
  left: 0; }

.reveal .overlay.overlay-preview .viewport iframe {
  width: 100%;
  height: 100%;
  max-width: 100%;
  max-height: 100%;
  border: 0;
  opacity: 0;
  visibility: hidden;
  transition: all 0.3s ease; }

.reveal .overlay.overlay-preview.loaded .viewport iframe {
  opacity: 1;
  visibility: visible; }

.reveal .overlay.overlay-preview.loaded .spinner {
  opacity: 0;
  visibility: hidden;
  transform: scale(0.2); }

.reveal .overlay.overlay-help .viewport {
  overflow: auto;
  color: #fff; }

.reveal .overlay.overlay-help .viewport .viewport-inner {
  width: 600px;
  margin: 0 auto;
  padding: 60px;
  text-align: center;
  letter-spacing: normal; }

.reveal .overlay.overlay-help .viewport .viewport-inner .title {
  font-size: 20px; }

.reveal .overlay.overlay-help .viewport .viewport-inner table {
  border: 1px solid #fff;
  border-collapse: collapse;
  font-size: 14px; }

.reveal .overlay.overlay-help .viewport .viewport-inner table th,
.reveal .overlay.overlay-help .viewport .viewport-inner table td {
  width: 200px;
  padding: 10px;
  border: 1px solid #fff;
  vertical-align: middle; }

.reveal .overlay.overlay-help .viewport .viewport-inner table th {
  padding-top: 20px;
  padding-bottom: 20px; }

/*********************************************
 * PLAYBACK COMPONENT
 *********************************************/
.reveal .playback {
  position: fixed;
  left: 15px;
  bottom: 20px;
  z-index: 30;
  cursor: pointer;
  transition: all 400ms ease; }

.reveal.overview .playback {
  opacity: 0;
  visibility: hidden; }

/*********************************************
 * ROLLING LINKS
 *********************************************/
.reveal .roll {
  display: inline-block;
  line-height: 1.2;
  overflow: hidden;
  vertical-align: top;
  perspective: 400px;
  perspective-origin: 50% 50%; }

.reveal .roll:hover {
  background: none;
  text-shadow: none; }

.reveal .roll span {
  display: block;
  position: relative;
  padding: 0 2px;
  pointer-events: none;
  transition: all 400ms ease;
  transform-origin: 50% 0%;
  transform-style: preserve-3d;
  backface-visibility: hidden; }

.reveal .roll:hover span {
  background: rgba(0, 0, 0, 0.5);
  transform: translate3d(0px, 0px, -45px) rotateX(90deg); }

.reveal .roll span:after {
  content: attr(data-title);
  display: block;
  position: absolute;
  left: 0;
  top: 0;
  padding: 0 2px;
  backface-visibility: hidden;
  transform-origin: 50% 0%;
  transform: translate3d(0px, 110%, 0px) rotateX(-90deg); }

/*********************************************
 * SPEAKER NOTES
 *********************************************/
.reveal aside.notes {
  display: none; }

.reveal .speaker-notes {
  display: none;
  position: absolute;
  width: 70%;
  max-height: 15%;
  left: 15%;
  bottom: 26px;
  padding: 10px;
  z-index: 1;
  font-size: 18px;
  line-height: 1.4;
  color: #fff;
  background-color: rgba(0, 0, 0, 0.5);
  overflow: auto;
  box-sizing: border-box;
  text-align: left;
  font-family: Helvetica, sans-serif;
  -webkit-overflow-scrolling: touch; }

.reveal .speaker-notes.visible:not(:empty) {
  display: block; }

@media screen and (max-width: 1024px) {
  .reveal .speaker-notes {
    font-size: 14px; } }

@media screen and (max-width: 600px) {
  .reveal .speaker-notes {
    width: 90%;
    left: 5%; } }

/*********************************************
 * ZOOM PLUGIN
 *********************************************/
.zoomed .reveal *,
.zoomed .reveal *:before,
.zoomed .reveal *:after {
  backface-visibility: visible !important; }

.zoomed .reveal .progress,
.zoomed .reveal .controls {
  opacity: 0; }

.zoomed .reveal .roll span {
  background: none; }

.zoomed .reveal .roll span:after {
  visibility: hidden; }