Since https://github.com/discourse/discourse/pull/25501 this behavior was broken. This PR attempts to fix it by being more fine grain.
Also note that this PR is moving `footer-nav-ipad` and `footer-nav-visible` to the `html` element and not the `body`. It makes more sense as we are already adding most of other global state class like `keyboard-visible` to the `html` element.
Tested on:
- chrome desktop
- safari ios - iphone
- PWA ios - iphone
- PWA ios - ipad
- DiscourseHub iphone
This commit sets a default of 0px for `--footer-nav-height` and set it only when `body.footer-nav-visible` allowing us to safely use `--footer-nav-height` wherever it will be needed if set.
In the past, our loading spinner implementation used Ember's loading substate. That meant that, when the site setting was toggled, there would be fundamental changes in the routing behavior.
This commit simplifies things so that the (non-default) loading spinner implementation is purely a styling thing, and behaves exactly the same as the spinner which appears under the 'slider' configuration when loading takes too long.
This does involve a slight UX change. Now, the entire page will be replaced by a loading spinner instead of just the relevant `{{outlet}}`. We strongly recommend sites use the new default 'slider' behavior.
This brings the functionality from https://github.com/discourse/discourse-loading-slider into Discourse core. Default behaviour remains the same - the new slider mode can be enabled using the new 'page_loading_indicator' site setting.
