Course avatar is not standard size

Hi, On the all courses page, course avatars on the right are not standard. Some are big and therefore take too much space, reducing the number of listings per page. My theme is repurposed without a child theme. so I cannot update it. I would be grateful if you can direct me to the file to edit to make the changes. I also left a support ticket on the old system at: tickets/6841 Thank you very much for your support