How to make images in Multicolumn smaller & compatible on all mobile devices

I am utilizing the Dawn theme and I would like to make images smaller than 1/3 width of the column.

I used the following coding: .multicolumn-card__image-wrapper–third-width {
width: 10% !important;
}

This was successful on all mobile iPhones except for my clients iPhone 12 , see screenshot for greyed out images. Can you please provide instructions of how to make the images smaller but compatible on mobile?