How to increase IPB Gallery lightbox size?

[Gauravk]

I tried inserted below codes in custom.css but it's not working

   }

.cGalleryViewImage > a {
     width: 1200px;
     height: 800px;

Can someone please help on how to increase Gallery lightbox size? Thanks.

https://carnity.com/gallery/image/439-dsc_0554jpg/?browse=1