Proposed APA comment on CSS inert (will post this week)

Dear colleagues,

Please find below my draft of a comment from us about CSS inert. This I hope
reflects the discussion. I intend to post it this week. A couple of notes:

0. Please check it out and let us know what you think, via this thread.
1. We need examples of non-APG carousels.
2. I have not included Chiara's (very interesting) DevTools suggestion,
because I think we are at the stage of having concerns about this feature
being added at all. However, later in the discussion (and to perhaps
complement HTML's inert attribute, which also doesn't affect styling), would
be a good time to convey Chiara's suggestion.

Propose comment coming up at the end of this message, below. Thanks again
for all of your input.

best regards,


Matthew

The Accessible Platform Architectures (APA) WG has reviewed this proposal
too, and has some concerns and questions.

We're very supportive of the trend to move widgets/features into CSS and
HTML, and away from needing JS to work. There have been lots of
accessibility wins because of this. We appreciate this carousel (and
foundational) work has similar goals. Though carousels present several
significant usability and accessibility challenges, they are widely used, so
the goal of making them more consistent, accessible, and efficient is
laudable.

* We're concerned that modifying the interactivity of elements, without
modifying their visual presentation, will lead to developers accidentally
rendering sub-trees of the DOM inert. Whilst this sort of mistake may seem
low-risk, speaking as an accessibility consultant, we see a lot of mistakes
along these lines, where the visual and non-visual go out-of-synch. It's a
significant risk, and significant consequences.

* In the same vein, we echo the concerns about 'un-inerting' - that it would
not be obvious to developers who've purposely 'inerted' a sub-tree that part
of that sub-tree has been un-inerted. @alice's [suggestion of limiting
'un-inerting' to the top
layer](https://github.com/w3c/csswg-drafts/pull/11178#discussion_r1845716939
), could address this.

* Having the un-inerting behaviour be inconsistent with the HTML inert
attribute seems like a significant DX issue.

* We are also concerned and wondering about the use cases where it makes
sense to use CSS inert rather than the HTML attribute? What other scenarios,
besides carousels, do you envisage for CSS inert?

* Whilst the APG pattern [1] demonstrates one way to make a carousel, we
find several different variations in the wild [?,?,?] that work differently.
Some allow the user to move focus via the keyboard to 'out-of-view' elements
- this avoids the need for the user to find navigation buttons, or learn
keyboard shortcuts, such as the arrow keys. Whilst not suitable everywhere,
these patterns don't seem to be encouraged by the existence of the `inert`
property.

[1] https://www.w3.org/WAI/ARIA/apg/patterns/carousel/

Matthew Atkinson
Head of Web Standards
Samsung R&D Institute UK
Samsung Electronics
+44 7733 238 020

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Received on Thursday, 13 March 2025 17:20:06 UTC