Bugzilla

I found the code that is switching between the different components for the slide previews:
```
let e = CSS.supports('selector(:popover-open)'),
t = CSS.supports('anchor-name', '--foo-bar');
h(e && t)
```
If I patch `CSS.supports()` to return `true` for `CSS.supports('anchor-name', '--foo-bar')` before the page is rendered then switching slides starts working for all slides. However, the popovers that are shown when hovering over a slide preview are misplaced, covering up most and sometimes all of the slide preview, making it hard or impossible to click on it, so an intervention wouldn't really fix the site.
So this is a combination of a missing feature (anchor positioning) in Firefox and a site bug in its fallback code for browsers that don't support anchor positioning yet.
(Commenting on User Story)
> platform:windows,mac,linux,android
> impact:workflow-broken
> configuration:general
> affects:all
> branch:release
> user-impact-score:1600
> diagnosis-team:layout

I found the code that is switching between the different components for the slide previews:
```
let e = CSS.supports('selector(:popover-open)'),
t = CSS.supports('anchor-name', '--foo-bar');
h(e && t)
```
If I patch `CSS.supports()` to return `true` for `CSS.supports('anchor-name', '--foo-bar')` before the page is rendered then switching slides starts working for all slides. However, the popovers that are shown when hovering over a slide preview are misplaced, covering up most and sometimes all of the slide preview, making it hard or impossible to click on it, so an intervention wouldn't really fix the site.
So this is a combination of a missing feature (anchor positioning) in Firefox and a site bug in its fallback code for browsers that don't support anchor positioning yet.