Buton 13

.btn-15 {
width: 130px;
height: 40px;
color: #fff;
border-radius: 5px;
padding: 10px 25px;
cursor: pointer;
transition: all 0.3s ease;
position: relative;
display: inline-block;
box-shadow:inset 2px 2px 2px 0px rgba(255,255,255,.5),
7px 7px 20px 0px rgba(0,0,0,.1),
4px 4px 5px 0px rgba(0,0,0,.1);
outline: none;
background: #b621fe;
border: none;
z-index: 1;
}
.btn-15:after {
position: absolute;
content: "";
width: 0;
height: 100%;
top: 0;
right: 0;
z-index: -1;
background-color: #663dff;
border-radius: 5px;
box-shadow:inset 2px 2px 2px 0px rgba(255,255,255,.5),
7px 7px 20px 0px rgba(0,0,0,.1),
4px 4px 5px 0px rgba(0,0,0,.1);
transition: all 0.3s ease;
}
.btn-15:hover {
color: #fff;
}
.btn-15:hover:after {
left: 0;
width: 100%;
}
.btn-15:active {
top: 2px;
}