custom.css

div.dz-gallery img {
    width: 100%;
}

.dz-gallery {
    width: 100%;
    margin: 0 auto;
}

.dz-grid {
    display: flex;
}

.dz-grid-col {
    flex: 1;
    padding: 0 .1em;
}

.dz-grid-col--2, .dz-grid-col--3, .dz-grid-col--4 {
    display: none;
}

@media (min-width: 768px) {
    .dz-gallery {
        width: 90%;
    }
    h1 {
        margin: 3em 0;
    }
    .dz-grid-col--2 { display: block; }
    .dz-grid-col {
        padding: 0 .5em;
    }
    img {
        margin-bottom: .8em;
    }
    .dz-grid-item:hover {
        cursor: pointer;

        .content {
            opacity: 1;
            transform: translateX(0);
        }
    }
}

@media (min-width: 1080px) {
    .dz-grid-col--3, .dz-grid-col--4 { display: block; }
    .dz-gallery {
        width: 80%;
    }
        h1 {
            margin: 5em 0;
    }
}