#1228: Other Spec Review: overscroll-behavior: chain

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Opened May 8, 2026

Specification

https://drafts.csswg.org/css-overscroll-1/#propdef-overscroll-behavior

Explainer

https://github.com/vmpstr/htmldemos/blob/master/gestures/overscroll-behavior-chain.md

Links

  • Previous early design review, if any: N/A
  • An introduction to the feature, aimed at unfamiliar audiences:
  • A description of the problems that end-users were facing before this proposal:
  • Alternatives considered:
  • Examples of how to use the proposal to solve the end-users' problems:
  • What do the end-users experience with this proposal:

All of the above are captured by the explainer: https://github.com/vmpstr/htmldemos/blob/master/gestures/overscroll-behavior-chain.md

The specification

Where and by whom is the work is being done?

  • GitHub repo: github.com/w3c/csswg-drafts/issues
  • Primary contacts:
    • @vmpstr, Google, Author
  • Organization/project driving the specification: Google
  • This work is being funded by: Google
  • Primary standards group developing this feature: CSSWG
  • Group intended to standardize this work: CSSWG
  • Incubation and standards groups that have discussed the design: CSSWG

Feedback so far

You should also know that...

No response

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Discussions

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Discussed May 18, 2026 (See Github)

Luke::Intent sent. Being reviewed by CSS. Decline?

Jeffrey: There was a presentation at BlinkOn that made it seeem that this was a piece of a complicated way of doing "drawers." That bigger system that this was part of seemed like it was worth looking at. Like, with carousels, the pieces looked fine but the overall system wasn't quite right. We might want to look in that way, but I don't know whether I have the expertise to actually perform that review.

Luke: Yes, this is part of a declarative overscroll thing from OpenUI: https://open-ui.org/components/overscroll-actions.explainer/. This is useful for that, but is a standalone isolated bit, which is why it's shipping as it is. It's useful on its own. No submission for the overall thing yet. Think it's ok to say that this piece is fine. Then do the larger thing when they request it.

Lola: Are there accessibility considerations for this? None in the explainer. Even a "no accessibility considerations" would be helpful. The explainer is short and assumes a lot of knowledge. Don't know what the technical terms mean. Can decline to review, but part of the reason is that there's not enough information.

Luke: Can comment that, and privacy and security. Can say there are no considerations, but should have it.

Matthew: +1 to please have an "accessibility considerations" section, even if it's empty. That shouldn't be special. Should have "all of them". Internationalization might be "obvious", but if there's a possibility, should encourage that too.

Jeffrey: I doubt it's obvious because right-to-left is quite likely to be affected by overscroll.

Luke: We should always encourage those sections. Might be obvious to me, but if someone else is reading, they should know it's been considered.

Matthew: Worth mentioning in the explainer explainer?

Jeffrey: I think it's already mentioned

Luke + Lola assigned.

Discussed Jun 1, 2026 (See Github)

Lola: I left draft comment. It seems fine and they have not given us much to work it. I don't see any critical accessibility issues. Some parts of it is good for cognitive accessibilities.

Luke: is there a chance to ask them on S&P section?

Lola: there is not much from them, but they included S&P section in the spec itself. It fullfils those requirements; however, I don't see accessibility consideration. Maybe worth asking them as it has positive impact on it.

Luke: I think this aspect is fine, the reason why they are doing that is more important.

Lola: do you want to review it Luke?

Luke: I don't have any concrete feedback. I think it is fine for you to draft a comment.

Lola: ok.

Discussed Jun 8, 2026 (See Github)

Lola to draft the comment.

Discussed Jun 22, 2026 (See Github)

bump

Discussed Jun 29, 2026 (See Github)

Luke: I will double check the minutes, but think the conclusion was we were happy with this overall, but provide some input on bits that were missing from the explainer. Will follow up with Lola.

Discussed Jul 6, 2026 (See Github)

Luke: We are happy with this, but also want to encourage inclusion of certain sections in the explainer, to help future reviewers.

Comment by @lolaodelola Jul 16, 2026 (See Github)

Hi @vmpstr,

Thank you for opening this review and apologies for the delay in getting back to you. We can see the benefit of this value for web authors, however, your explainer is missing key sections which make it difficult to understand what impacts you have or haven't considered on web users. We'd especially like to know what accessibility considerations are relevant here, even if none.

We do have a question about the naming. chain "allows chaining and non-local boundary default actions disallows local boundary default actions" while auto "allows chaining, local and non-local boundary default actions", this is confusing. We can envision a scenario where a web author wants to allow chaining without disallowing local boundary default actions and using chain to do so when they'd actually want auto.

Staying on the naming theme, is chain here a verb or a noun? I.e. is the overscroll-behavior a chain or is the overscroll-behavior being chained? The language in the explainer indicates to me that it's a verb and if so, I want to highlight the Web Design Principle on CSS Naming:

The names of CSS properties are usually nouns, and the names of their values are usually adjectives (although sometimes nouns).

We'd encourage the group to consider a name for the value that better highlights the difference in behaviour from auto and follows the design principle. With this in mind, we're resolving as satisfied with concerns.