If you still have the same problem. You don’t need an additional coding. Go to your section-multicolumn.css file and just change the percentage in line 23 e.g. to 15% →
.multicolumn-card__image-wrapper–third-width {
width:15%;
}
Don’t forget to select in the editing mode of your theme : one-third width of the column as the image width. (See right side of the picture in the original post).
Hope this helps.