.landing {
    z-index: 1;
}

.photo {
    position: absolute;
    width: 100%;
    height: 100%;
    top: 0;
    left: 0;
    z-index: -1;
}

.box-photo {
    display: flex;
    flex-wrap: wrap;
    width: 100%;
    height: 50%;
}

.item-photo {
    width: 20%;
    max-height: 100%;
    opacity: 0%;
}

.item-photo:hover {
    opacity: 50%;
}