<a href="#" class="cp_btn">button</a>

a.cp_btn {
  position: relative;
  display: block;
  width: 160px;
  padding: 0.8em;
  text-align: center;
  font-weight: bold;
  text-decoration: none;
  color: #FFF;
  text-shadow: 0 0 5px rgba(255, 255, 255, 0.0);
  background: #1A237E;
  border-radius: 4px;
  transition: .4s ease-in-out;
}
a.cp_btn:hover {
  text-shadow: -6px 0px 15px rgba(255, 255, 240, 0.83), 6px 0px 15px rgba(255, 255, 240, 0.83);
  transition: .4s ease-in-out;
}