.img-zoom-link {position: relative; display: block;}
.img-zoom-link:before {
    content: url(../../img/zoom.png);
    display: table;
    width:50px;
    height:50px;
    border-radius: 50%;
    position: absolute;
    z-index: 1;
    top:calc(50% - 25px);
    left:calc(50% - 25px);
    background-color: rgba(114, 192, 44, 0.5);
    color: #ffffff;
    opacity: 0;
    transition: opacity 0.5s ease;
    padding: 12px 0 0 12px;
}
.img-zoom-link:hover:before {
    opacity: 1;
}