Light box Image Full Screen

Hello!

I’m trying to recreate a existing site, this is the site i’m replicating here: https://www.adamprout.com/inventory/ and this is the site im currently building: http://adamprout2.uk.w3pcloud.com/inventory/

On the existing site, the gallery images when clicked on fill the screen, and you have to scroll to see the rest of the images.

I’m using the next gen gallery to re create this, and the only way I can display the light box is for the image to contain the height of the screen.

Is there a way that I can get this image to fill the screen completely when clicked on using the next gen settings?

Any thoughts would be greatly appreciated!

Thank you in advance.

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