Hi,
I'm having this same issue even after finding the image id
https://sawfish-reed-w87p.squarespace.com
code i used was
@media screen and (max-width:640px) {
div#block-yui_3_17_2_1_1592145115756_295 img {
width: 30% !important;
height: auto !important;
transform: translateX(-50%);
left: 50% !important;
}
div#block-yui_3_17_2_1_1592145115756_295 .image-block-wrapper {
padding-bottom: 50% !important;
}
}