/* Preserve the theme's existing product-image hover behaviour. */
.woocommerce ul.products li.product a.woocommerce-LoopProduct-link img:not(.product-image--hover):hover,
.woocommerce ul.products li.product a.woocommerce-loop-product__link img:not(.product-image--hover):hover {
    opacity: unset !important;
    transition-duration: 0.6s !important;
}

.wc-product-image-wrapper {
    position: relative;
}

.wc-product-image-wrapper img {
    display: block;
    width: 100%;
    height: auto;
}

.wc-product-image-wrapper img.secondary-img {
    position: absolute;
    top: 0;
    left: 0;
    width: 100%;
    height: auto;
    opacity: 0;
    transition: opacity 0.4s ease-in-out;
}

.wc-product-image-wrapper:hover img.secondary-img {
    opacity: 1;
}