.button,
.button span {
  position: relative;
  display: inline-block;
}
.button span {
  padding: .40em 2em;
  background: -webkit-linear-gradient(#11bbee , #aabbee);
  background: linear-gradient(#11bbee , #aabbee);
  border: 1px solid #11bbee;
  border-radius: 4px;
  color: #fff;
  text-decoration: none;
  text-align: center;
  -webkit-transition: .3s ease-in-out;
  transition: .3s ease-in-out;
}
.button::after {
  position: absolute;
  bottom: -15px;
  left: 50%;
  z-index: -1;
  content: '';
  width: 100%;
  height: 24px;
  background-color: rgba(0,0,0,.1);
  border-radius: 50%;
  -webkit-transform: translateX(-50%);
  transform: translateX(-50%);
  -webkit-transition: .3s ease-in-out;
  transition: .3s ease-in-out;
}
.button:hover span {
  -webkit-transform: translateY(-10px);
  transform: translateY(-10px);
}
.button:hover::after {
  width: 70%;
  height: 18px;
}