Urgent small website fix need completion today. Responsive website Code adjustment

This website is a modified theme that has a gallery of images that adjusts based on screen size. (see image attached) All I need done is the script modified so the images fills the gap on the right hand edge. I have had a CSS programmer attempt to fix this but has informed me it could be a java script setting. I need this worked on straight away. Do not bid if you can't do the job now. If you now what you are doing it should be a simple fix. Please type CODE at the start of your bid response. Happy Bidding!