Image randomly increased by 20px x 20px

I have a map image that is 680×800 set up pop up with easy fancy box on the homepage of our work in progress https://www.salamatphilippines.com. In easy fancy box I have the “Dimensions” settings set to 680×800 with a margin of 20 (not sure what that means, but could be the reason why the image is 20px larger).

The issue is that the image quality is distorted because it’s being displayed 20px x 20px larger then it’s supposed to be, it’s displaying at 700×820, when it’s supposed to be 680×800. I’m not sure if I’m missing a setting? Any ideas?

Thank you!