Responsive issue on smartphone with TwentyTwelve/FooGallery/Page Builder

As I don’t know where the problem is, so I am posting here.

I have a problem with my gallery pages on smartphone.
Here is the link: https://www.lgphotography.fr/wordpress/portfolio/fauna/

Here is the print from my cel phone:
https://www.lgphotography.fr/Help/IMG_20151125_183219.jpg
The thumbnail size does not adapt to the screen.

I have tried with sevral themes and found only one (I was using before) on which it is really is OK (Snapshot Plus).
This is the way it should look: https://www.lgphotography.fr/Help/IMG_20151125_183628.jpg

Here are my current settings:
https://www.lgphotography.fr/Help/FooGallery.jpg
https://www.lgphotography.fr/Help/PageAjust.jpg
https://www.lgphotography.fr/Help/PageAjust-builder.jpg
https://www.lgphotography.fr/Help/PageBuilder.jpg

Can anyone help?