.ex1:active {
  transform: scale(.88);
  transition: transform 0.1s;
}

.cercle {
  width: 0px;
  height: 0px;
  position: absolute;
  background: white;
  border-radius: 50%;
}

.anim {
  opacity: 0.7;
  animation: touch 0.8s ease-out;
}

@keyframes touch {
 40% {
    opacity: 0.7;
  }
  100% { 
    width: 100px;
    height: 100px;
    opacity: 0;
    margin: -50px;
  }
}