In your demo for the newest JCE Pro there's a snippet "grid-gallery", that's very easy to use.
I copied the source code and inserted it in the JCE plugin preferences - and it worked out fine.

There's only one small problem:
In your demo - when in editing and preview mode - the 3 images are next to each other, like CSS "display:flex".

In my pure protostar test page the images are arranged one below the other, - in editor mode and in preview mode - like simple paragraphs or divs .

I could live with this small issue, but for my client it's distracting.
How and where did you insert the CSS style (or something else) that's effective in the editor?

Or is "grid-gallery" not a snippet but a template? Then: Would you be so kind to share the source code?

The screenshots are not visible. I'll try it as attachments.

Editor Demo:


My Test Page


UteS

Ryan,
that's exactly what I was looking for. 😃
In addition, it's very easy to customize the snippet code for 2 / 3 / 4 images e.g. for a small series.

Many thanks!

Ute S.