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

a.cp_btn {
  position: relative;
  display: block;
  width: 160px;
  padding: 0.8em;
  text-align: center;
  text-decoration: none;
  color: #FFF;
  background: #26C6DA;
  border-bottom: 2px solid #00838F;
  border-radius: 4px;
  box-shadow: inset 0 2px 0 rgba(255,255,255,0.2), 0 2px 2px rgba(0, 0, 0, 0.2);
}
a.cp_btn:active {
  border-bottom: 2px solid #26C6DA;
  box-shadow: 0 0 2px rgba(0, 0, 0, 0.3);
}