.sm {
  text-align: center;
}
.link {
  display: inline-block;
  width: 90px;
  height: 90px;
  margin: 10px;
  border-radius: 30%;
  box-shadow: 9px 9px 18px #bebebe, -9px -9px 18px #fff;
  position: relative;
  overflow: hidden;
  line-height: 90px;
  font-size: 30px;
  transition: 0.8s;
  text-align: center;
}
.link:hover {
  color: #fff;
}