Hi again,
I've implemented a pretty straightforward full-screen gallery and tried to view it in Safari on the iPhone.
The gallery, which is a series of 1200x800 images, works fine on desktop. On iPhone, the first thing I notice is the images are scaled to window height, so all my landscape portraits of people are now just big close-ups of noses and other awkward crops. But that's not the problem as such.

The problem is that if I turn the site/phone sideways (landscape) while the gallery is open, then instead of adjusting to the new fixed width, the images scale off infinetly, kind of zooming in to a single pixel, or scaling up exponentially as though the new expanded width were matched by a newly expanded height. So, instead of moving from a tall narrow frame to a short wide frame and fitting accordingly, it's as if the height change were scaled proportionate to the width change, the result being only a magnified crop of the top-left image corner is visible and the gallery navigation and menu are way outside of the visible area.

The gallery ONLY works in landscape if I am *already in* landscape mode when I open it for the first time. Switching while open completely confuses it, destroying the navigation in a way that I can only escape from by reloading or closing the window. After confusing it, it confuses the full-screen background image on other pages too, which just scale endlessly until they settle having formed weird long pages, three times the height of the viewable area. And since clearing the cache on a mobile device is easier said than done, no visitor is going to deal with that.

Thoughts?

Safari. Current iOS. iPhone 6S+