.reference-gallery__list {
    display: flex;
    flex-wrap: wrap;
    margin-left: -10px;
    margin-right: -10px;
    margin-bottom: 0;
}
.reference-gallery__list:last-child {
    margin-bottom: -20px;
}
.reference-gallery__item {
    flex: 0 0 auto;
    width: 25%;
    padding: 0 10px;
    margin-bottom: 20px;
}

@media (max-width: 991px) {
    .reference-gallery__item {
        width: 33.33%;
    }
}

@media (max-width: 576px) {
    .reference-gallery__item {
        width: 50%;
    }
}