body {
    width: 90%;
    max-width: auto;
    margin: 2em auto;
    font: .9em/1.2 Arial, Helvetica, sans-serif;
}
.gallery-container {
    column-count: 4;
    column-gap: 20px;
}

.gallery-container > div {
    break-inside: avoid;
    margin-bottom: 4px;
    border-radius: 20px;
    overflow: hidden;
}

.gallery-container > div img {
    display: block;
    width: 100%;
    height: auto;
    border-radius: 10px;
}

@media (max-width: 768px) {
    .gallery-container { column-count: 3; }
}

@media (max-width: 480px) {
    .gallery-container { column-count: 2; }
}