Thumbnail image and excerpt overflow in [one_fourth_last]

The [one_fourth] shortcode works great. I have three in a row and all the image thumbnails and excerpt text are the same size and width. When I add the final [one_fourth_last], the thumbnail and excerpt text overflow the div (omsc-one-fourth omsc-last), making them slightly larger than the first three. How do I make the last shortcode display at the same size as the first three?

Thanks!

https://www.ads-software.com/plugins/display-posts-shortcode/