Full-Screen Popup when pressed

I need help building/finding a plugin that allows for a full-screen popup (modal?) that is similar to this when pressed on an image. I am trying to rebuild my school’s website and I couldn’t find out how this site does this. I have tried many plugins trying for the same effect but none of them work well at all. They all seem to be super tiny boxes and unresponsive.

I hope this makes since and that I posted this in the correct place.

Thank you!

• This topic was modified 1 year, 10 months ago by James Huff. Reason: link moved to proper field

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