Displays incorrectly on shop page

I know it’s not been updated in years but it works great on my product page. However, on my shop page the overlay is too big and doesn’t scale down like I thought it should. It’s such a shame as otherwise this is exactly what I need.

My site is in dev but I have included a screenshot in the link as an example.

Is there any help out there for this plugin?

The page I need help with: [log in to see the link]