Lightbox images in full resolution

Site URL: http://www.xaviervoirol.ch

Is there a way to change the display size of an image when it appears in the lightbox? When I click on a thumbnail, vertical images come with a size of 750 x 1125 px, but I would like them to be a bit bigger. At least a height of 2000 px or, even better, at full uploaded size (3000 x 4000 px). Actually, I need a hack to override the presence of the "?format=750w" taht appears at the end of the image URL.

Try adding to Design > Custom CSS

.sqs-lightbox-open .sqs-gallery-design-stacked-slide img {
    width: 100% !important;
    left: 0 !important;
    height: auto !important;
    top: -100% !Important;
}