Uniform Width for Featured Images on Front Page

First, I love the Amadeus theme, and am working with it on an as yet unlaunched site. I have several tweaking issues that I will address one by one.

This one: Is there a way to make each of the Featured Images for the posts on the first/front page a uniform width? Ideally, I would like each image to fill out the space between the faint gray lines of the boxes that make up each entry.

Thanks in advance!