Adding formatted captions only in the lightbox view of image galleries

I'm very new to Squarespace and I'm struggling to make this happen.

I'm starting to build an art portfolio website. I have masonry-style, Lightbox-enabled grids of different art pieces, and I'm using captions for the descriptions of each piece. I'd like the captions to be hidden in grid view but visible under the image in Lightbox view.

Ideally, I'd like the captions to be right-aligned throughout and capable of italicizing the title in the descriptions (to follow the format of Work Title, year, medium, dimensions). VERY ideally, I'd also be able to add longer descriptions under some select images. But I'll settle for just having the descriptions hidden in grid view and show up in Lightbox view! 

I've found and tried out a couple custom CSS and footer code injection codes, but haven't had any success.

3 hours ago, hek said:

I'm very new to Squarespace and I'm struggling to make this happen.

I'm starting to build an art portfolio website. I have masonry-style, Lightbox-enabled grids of different art pieces, and I'm using captions for the descriptions of each piece. I'd like the captions to be hidden in grid view but visible under the image in Lightbox view.

Ideally, I'd like the captions to be right-aligned throughout and capable of italicizing the title in the descriptions (to follow the format of Work Title, year, medium, dimensions). VERY ideally, I'd also be able to add longer descriptions under some select images. But I'll settle for just having the descriptions hidden in grid view and show up in Lightbox view! 

I've found and tried out a couple custom CSS and footer code injection codes, but haven't had any success.

You can get reference from @tuanphan's solution in this post

Hope it makes sense

The code works somewhat for me, but it doesn't really fit nicely on the image. I tried editing it but it seems to break the code completely. (I'm a graphic designer with very basic knowledge of html/css). Any idea on what I should do?