Thanks, Stephen, for all this advice.
My main takeaway: to ensure this works, my gallery must be the only element on my web page and its dimensions must be 100% by 100%.
I ran two new tests: without a table (92%) and 100-100%.
They all work well on a Windows PC.

Ref:
http://lepec.and.co.free.fr/photo/2025gando
galleryHeight="92%"
<table
Results on iPhone IOS > >> SplashPage

New 1:
http://lepec.and.co.free.fr/photo/2025gandoxx
galleryHeight="92%"
<header
Results on iPhone IOS > >> SplashPage

New 2:
http://lepec.and.co.free.fr/photo/2025gandox
galleryHeight="100%"
Results on iPhone IOS > >> No SplashPage but 1 image!?

For now, I prefer New 1, because I don't have the gallery directly with New 2.
Why ou what do you think?

Splash Page Display Issue on Mobile Devices

Hello,
I believe I’m experiencing the same SPASH PAGE problem that vincefx reported back in 2023.

I've been using JuiceBox for several years, and I've noticed that my gallery does not display correctly on mobile devices (iPhone – tested on Safari, Firefox, and Chrome). It works perfectly on a Windows PC, but when I click a link to access the gallery from my smartphone : a fullscreen version of the first image.

The JavaScript seems to load properly (I’ve checked), but the gallery container is replaced by the first photo in the list.

From what I understand, this might be related to how the script is embedded. I suspect you might recommend avoiding the use of a table for layout purposes (may be to be replace by CSS flexbox ?), but before making any changes, I’d prefer to ask.

Thanks in advance for your help!

The link to my last website (I try to do my best with index.html & config.xml ;-) : http://lepec.and.co.free.fr/photo/2025gando/
The link to an older one with the same problem :  http://fabien.photo.free.fr/limousin2024/

Thank you for your help