Format gallery to three across on mobile

I'm trying and failing to get the gallery of three square images to show as 3 across on mobile. Any help would be greatly appreciated! 
 

You can use this CSS code

@media screen and (max-width:767px) {
[data-section-id="65bba9e03ca5fa0524316b43"] .gallery-grid-wrapper {
    grid-template-columns: repeat(3,1fr) !important;
}
}