Administered by:
Used to always recommend kirbycms but not sure I can now. First thing I tried didn’t work, so I asked on the forums. Got essentially ’what did you expect, we don’t say everything works’ for the demo theme it comes with. The demo theme that is ‘fully annotated’ but doesn’t say it’s only a partial thing.
I was hoping not to have to add my own patches to the core of a cms to style a gallery of images. 
Trying to explain that the messaging says one thing (a working thing you can extend as much as you like) but their ‘philosophy’ is different (barebones thing you need to make functional yourself) and getting nowhere. “But we’ve always done it like this”
Ah well.
@aegir I see it just as a feature that the frontend is not opinionated. It's all *yours* to come up with what you see fit as a gallery. When you're looking for ready-made themes where someone else decided this for you, you could have a look at https://getkirby.com/themes 
if there's something you like. Cheers!