.img-overlay::before {
    content: ' ';
    display: block;
    height: 50%;
}

.img-overlay {
    position: absolute;
    top: 0;
    bottom: 0;
    left: 0;
    right: 0;
    text-align: center;
}

.custom-thumbnail {
    padding: 0 !important;
    margin: 0px 0px 15px 18px;
    background-color: #d5d5d5;
    border: 1px solid #bbb;
}

.custom-thumbnail .img-wrapper {
    text-align: center;
}

.custom-thumbnail .img-overlay button {
    display: none;
}

.custom-thumbnail .img-overlay:hover button {
    display: unset;
}