/* Thumbnail hover overlay */
.product-thumbnail:before {
    content: '';
    position: absolute;
    top: 0;
    left: 0;
    bottom: 0;
    right: 0;
    background: rgba(255, 255, 255, 0.5);
    opacity: 0;
    transition: opacity 0.2s;
}
.product-thumbnail:hover:before {
    opacity: 1;
}