I haven't tried Firefox mobile yet, but I will download it to test. Sounds to me like it doesn't update the page height after changing the browser bar's height.

I think Firefox mobile isn't capable of handling "sticky" positioning. Try disabling Settings / Tiger / Site / Top bar / Stick to top.

Aren't any of the full-screen options turned on on the Settings / Tiger / Lightbox page?

Can you please test if disabling "Go full-screen during slideshow" fixes it?

It's a bug in Firefox mobile (market share 0.29%), which I believe they should address.

Handling the browser bar removal seems to be a hard-to-crack problem for most browsers. If you want the browse bar to be removable, you have to scroll the page up. But that only works if the page is larger than the screen. Lightboxes are usually full-screen layouts, which don't allow vertical scrolling. This is why some of my skins go full-screen automatically on mobile devices when you enter the lightbox. But that's not foolproof either. This seems to work best on WebKit-based browsers (Chrome, Edge, Opera). Safari and, as it seems, Firefox are lagging behind in implementing the best logic.

I continued to think about this, and I'm only half satisfied.

I chose to NOT select "Switch to full screen while in lightbox" because I find that systematically displaying images in full screen on desktop computers is no longer really useful. "Modern" screens are increasingly larger; display areas of over 30" are common, and IMHO always displaying images in full screen is not desirable on such screens, whether in the lightbox or the slideshow.

On the other hand, it's the opposite on a mobile device (by which I mean a phone or tablet). Their screens are small, and I think it's beneficial to use the entire screen area for a better presentation of the images, even if this is less true on a tablet.

So here's the dilemma: either I choose the first option with a display optimized for desktop, but with display issues on Firefox mobile (other people I know also use it), or I choose a full-screen display that will be fine on mobile, but unsuitable for desktop Which one should I choose?

Ideally, regardless of the Firefox issue, the best solution would be to be able to choose which display mode to use on which device. Full screen on mobile and normal elsewhere seems perfect to me, but it should be up to the users to choose what they want. I'm well aware that introducing this feature would add a bit of complexity to Tiger's GUI.

I tested it by tweaking the JavaScript in a modified version of Tiger, and I'm very happy with the result: the images display as I want, where I want, and I no longer have the problem of the footer displaying in Firefox mobile.

@Laza FYI, if you decide to implement something like this in the future, I advise you not to use the User-Agent to identify whether the album is displayed on a mobile device or not. Indeed, I realized after quite some time that the User-Agent returned by my Samsung tablet running Android is

Mozilla/5.0 (X11; Linux x86_64; rv:147.0) Gecko/20100101 Firefox/147.0

Why? Because Mozilla decided that to improve the display of websites on tablet screens, it would make them appear as desktop machines by tricking the User-Agent. This is configurable (but well hidden in the settings), but it's enabled by default.

For detection without using User-Agent, I based my approach on https://developer.mozilla.org/en-US/docs/Web/HTTP/Guides/Browser_detection_using_the_user_agent#alternatives_to_ua_sniffing :

if (navigator.maxTouchPoints > 1) ...

works but could trigger false positives on laptop touchscreens (it's still better than nothing.). Other solutions exist, but they aren't necessarily more effective; see https://stackoverflow.com/a/20293441 .

There you go, I hope this gives some ideas

The "Go full screen only on mobiles" option is already in the Story skin. I'll transplant it to Tiger. It detects the screen size to determine whether it's a mobile device. If any dimension is smaller than 640px, it goes full-screen when entering the lightbox.