@import url(https://fonts.googleapis.com/css?family=Roboto:400,700);
html, body {
  width: 100%;
  height: 100%;
  margin: 0;
  -webkit-user-select: none;
     -moz-user-select: none;
      -ms-user-select: none;
          user-select: none; }

body {
  display: -ms-flexbox;
  display: flex;
  font-family: Roboto, "Helvetica Neue", sans-serif;
  font-size: 18px;
  perspective: 1000px;
  background-color: #f5f5f5;
  -ms-flex-direction: column;
      flex-direction: column;
  -ms-flex-pack: center;
      justify-content: center;
  -ms-flex-align: center;
      align-items: center; }

.description {
  margin-top: 50px;
  text-align: center;
  color: #999;
  transition: opacity 0.3s ease; }

.description a {
  color: #4A9DF6;
  text-decoration: none; }

.btn.is-open ~ .description {
  opacity: 0; }

.btn {
  display: block;
  position: relative;
  width: 200px;
  height: 80px;
  transition: width 0.8s cubic-bezier(0.23, 1, 0.32, 1), height 0.8s cubic-bezier(0.23, 1, 0.32, 1), transform 0.8s cubic-bezier(0.175, 0.885, 0.32, 1.275);
  transform-style: preserve-3d;
  transform-origin: 50% 50%;
  text-align: center; }

.btn-front {
  position: absolute;
  display: block;
  width: 100%;
  height: 100%;
  line-height: 80px;
  background-color: #F44336;
  color: #fff;
  cursor: pointer;
  backface-visibility: hidden;
  -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
  transition: background 0.15s ease, line-height 0.8s cubic-bezier(0.23, 1, 0.32, 1); }
  .btn-front:hover {
    background-color: #f77066; }

.btn-back {
  position: absolute;
  width: 100%;
  height: 100%;
  background-color: #eee;
  color: #222;
  transform: translateZ(-2px) rotateX(180deg);
  overflow: hidden;
  transition: box-shadow 0.8s ease; }
  .btn-back p {
    margin-top: 27px;
    margin-bottom: 25px; }
  .btn-back button {
    padding: 12px 20px;
    width: 30%;
    margin: 0 5px;
    background-color: transparent;
    border: 0;
    border-radius: 2px;
    font-size: 1em;
    cursor: pointer;
    -webkit-appearance: none;
    -webkit-tap-highlight-color: rgba(0, 0, 0, 0);
    transition: background 0.15s ease; }
  .btn-back button:focus {
    outline: 0; }
  .btn-back button.yes {
    background-color: #2196F3;
    color: #fff; }
    .btn-back button.yes:hover {
      background-color: #51adf6; }
  .btn-back button.no {
    color: #2196F3; }
    .btn-back button.no:hover {
      background-color: #ddd; }

.btn[data-direction="left"] .btn-back,
.btn[data-direction="right"] .btn-back {
  transform: translateZ(-2px) rotateY(180deg); }