div a{
  margin: 0 auto;
  text-decoration: none;
  color: #fff;
  font-size: 19px;
  line-height: 1;
  position: relative;
  width: 120px;
  height: 120px;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: all 0.3s ease-out;
}

div a:before{
  content: "";
  display: block;
  position: absolute;
  background-color: #ccc;
  border-radius: 100%;
  top: 50%;
  left: 50%;
  margin: -60px 0 0 -60px;
  width: 120px;
  height: 120px;
  z-index: -2;
  transition: all 0.1s ease-out;
}
div a:hover:before{
  width: 130px;
  height: 130px;
  margin: -65px 0 0 -65px;
}