.link {
width: 150px;
height: 40px;
background: #ccc;
position: relative;
display: inline-flex;
justify-content: center;
align-items: center;
}
.link:before {
top: -5px;
left: -5px;
z-index: -1;
content: '';
width: 25px;
height: 25px;
display: block;
background: orange;
position: absolute;
}