.product-item:hover {
    opacity: 1;
}

.product-item {
    transition: opacity 0.3s ease;
}

.product-item:hover ~ .product-item {
    opacity: 0.5;
}

.row:hover .product-item {
    opacity: 0.5;
}

.row:hover .product-item:hover {
    opacity: 1;
}