Maintain 2 and 3 column layout on mobile

Site URL: https://www.andrewmarston.com/photo

On this page is there a way to main the 2 and 3 column layout of the 7 images at the top of the page on mobile devices? Currently in portrait orientation on my smartphone the page switches to displaying the images full width. I've been wrestling with various media queries for awhile now but the Squarespace code always overrides me.

adding to Home > Design > Custom CSS

@media screen and (max-width:640px) {
div#page-section-5e5d7f7555bd5e64fddf6e3b>.row:not(:first-child)>.col {
    width: 50% !important;
    float: left !important;
}
}