.div_gallery_piccola,
.div_gallery_media {
    width: calc(25% - 8px) !important;
    background-image: none !important;
    height: auto !important;
    float: left !important;
    margin: 4px !important;
    box-sizing: border-box;
    overflow: hidden;
    border-radius: 6px;
}

@media (max-width:900px) {

    .div_gallery_piccola,
    .div_gallery_media {
        width: calc(33.33% - 8px) !important;
    }
}

@media (max-width:600px) {

    .div_gallery_piccola,
    .div_gallery_media {
        width: calc(50% - 8px) !important;
    }
}

.forum_thumb {
    width: 100%;
    aspect-ratio: 1/1;
    object-fit: cover;
    display: block;
    border-radius: 6px;
}