Huge featured images on PCs

While the featured image sizes correctly on tablets and phones, it is enormous on a PC, and only the top of it is visible.

I’ve tried every combination of blog settings and have removed the ‘show thumbnail’ setting, but that makes no difference.

I also have a screen print if you need it, which shows what I see on my laptop, but not sure how to attach it here.

Hope you can help. Many thanks in advance.

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