catmatch.css

/* Reset */
* {
     vertical-align: baseline;
     font-family: Helvetica, sans-serif;
     font-size: 12pt;
     color: black;
     text-decoration: none;
     border: none;
     padding: 0;
     margin: auto;
}

.screen {
  display: none;
  width: 100%;
  height: 100%;
  position: absolute;
}

.padding {
  height: 35%;
}

h1 {
  text-align: center;
  font-size: 3em;
  margin-bottom: 0.5em;
}

p {
  text-align: center;
}

a {
  font-size: 2em;
  background-color: skyblue;
  padding: 0.5em 1.5em;
  border-radius: 0.25em;
}

ul {
  display: block;
  list-style: none;
}

li {
  width: 22%;
  height: 30%;
  margin: 1% 1.5%;
  float: left;
  -moz-transform-style: preserve-3d;
  -moz-transition: 0.5s;
  -webkit-transform-style: preserve-3d;
  -webkit-transition: 0.5s;
}

img {
  width: 100%;
  height: 100%;
  border-radius: 0.75em;
  -moz-backface-visibility: hidden;
  -webkit-backface-visibility: hidden;
}

.front {
  position: absolute;
  -moz-transform: rotateY(180deg);
  -webkit-transform: rotateY(180deg);
}

.flipped {
  -moz-transform: rotateY(180deg);
  -webkit-transform: rotateY(180deg);
}

.dissolve {
  opacity: 0;
  -moz-transition:opacity 0.75s linear;
  -webkit-transition:opacity 0.75s linear;
}