prettyPhoto too small in mobile browsers

url reference: https://realtreelandscapes.com/hardscapes/

Hi,
In the above url, I’m using Nextgen gallery combined with prettyPhoto. As you click on a gallery thumbnail, it opens up all photos using prettyPhoto.

It works really well and I’m pleased with it. However when being viewed on a mobile browser (iPhone/Android phones only – tablets are fine), the lightbox appears too small and quite difficult to navigate.

How can I set it to maximize the screen size on a mobile browser?

Thanks!
Abel

https://www.ads-software.com/extend/plugins/prettyphoto-media/