Hi Steven, thanks a lot for your reply, which was very helpful!

I didn't actually implement the galleryWidth property, but you made me think about looking for more fitting ones, and I found "frameWidth": maybe I didn't make it clear (sorry) but I was actually referring to expanded fullscreen.

But then I realized that - somehow - the property also affected the normal view, and I tried to figure out another solution: I found out that the fullscreen container has a generated id #jb-glry-dlg, which remains the same regardless on which page the module instantiates the gallery  through the Drupal website, and regardles the number of the galleries rendered in the same page: in this second case, the div#jb-glry-dlg will contain the fullscreen view for all the galleries.

Upon this, I created some css rules with the restricted scope #jb-glry-dlg to adjust slightly the image size (the no need to fix the alignment), the caption width and the positioning of the slider triggers.

And... it seems to work now.

If I think that for mobile devices (not only lower resolutions) the page is already correctly rendered, without my changes to be rendered, maybe I found a good fallback.

I thought it was worth to share also for other users, but if you think that something sounds somehow "dirty" in this solution, please tell me, so I - and someone else eventually - can approach the issue even better.

Thanks a lot for the precious and rapid support!

Best,
Giovanni.