How to target and style any new masonry gallery item?

Hi,
will be very grateful for an advice…

Problem:
I have several pages with masonry gallery and items.
I have the gallery on main navigation level ( e.g. Inscenace) and on submenu level (e.g. Inscenace >> The Losers)
I have used two groups of images (because of the path to link e.g. go to /../kolaps/ or /kolaps/
Thats ok…

BUT ALWAYS I ADD A NEW ITEM (now added Hrdinove) TO MASONRY GALLERY, I NEED TO STYLE THE NEW ITEM SEPARATELY IN CSS…
And my client wants to add these himself and do not knows css styling…

Please is there a css code or selector I can use for any (all) new items of masonry gallery to style
1) the H3 headline
2) the masonry image container

I USE THE ID and CSS class in masonry gallery :
inscenace-masonry-gallery

Right now I try to target any new item with css selector like this, but thats not the way I need it :
e.g. #av-masonry-1-item-11012 > figure:nth-child(2) > figcaption:nth-child(2) > div:nth-child(1) > div:nth-child(1) > h3:nth-child(2),

e.g. #av-masonry-1-item-11012 > figure:nth-child(2) > div:nth-child(1) > div:nth-child(1)

BIG THANKS
Kind regards
Jan