.reveal {
  opacity: 0;
  transform: translate3d(0, 100px, 0);
  transition: opacity 0.8s, transform 0.8s;
}
.reveal_visible {
  opacity: 1;
  transform: translate3d(0, 0, 0);
}



.box {
  background: #2ecc40;
  margin: 2%;
  border-radius: 10px;
  display: inline-block;
}
.small .box {
  width: 20%;
  padding-bottom: 20%;
}



.medium .box {
  width: 44%;
  padding-bottom: 25%;
}

.big .box {
  background-color: #01ff70;
  width: 94%;
  padding-bottom: 30%;
}