.quickzoom-button {
    position: absolute; margin-top: -4em; left: 0; right: 0; text-align: center;
    opacity: 0;
    transition: opacity .25s ease-in-out;
    -moz-transition: opacity .25s ease-in-out;
    -webkit-transition: opacity .25s ease-in-out;
    pointer-events: none;
}
.product-item:hover .quickzoom-button {
    opacity: 1;
}