<a href="#" class="cp_btn">button</a>
a.cp_btn {
display: block;
text-align: center;
text-decoration: none;
color: #FF5722;
width: 120px;
height: 120px;
line-height: 120px;
border: double 4px #FF5722;
border-radius: 50%;
vertical-align: middle;
overflow: hidden;
transition: .6s;
}
a.cp_btn:hover {
transform: rotateY(360deg);
}