mdn/content

Document accessibility considerations for Custom Highlight API

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#43408 opened on Mar 11, 2026

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Content:WebAPIgoal: best practiceshelp wanted

Description

MDN URL

https://developer.mozilla.org/en-US/docs/Web/API/CSS_Custom_Highlight_API

What specific section or headline is this issue about?

Missing Accessibility section

What information was incorrect, unhelpful, or incomplete?

The site should have a paragraph about how the API is supported by assistive technology, like many other MDN pages (e.g. <mark>). Correct me if I'm wrong, but as of right now there does not seem to be much information about the support of assistive technology with the Custom Highlight API (besides a CSS wg thread from 2021). It is important to add this kind of information, because people using this API might not be aware of the implications using this, since from the outside it could look like it is well supported. There is no mention what the "type" is supposed to do and how well it is supported in screen readers.

What did you expect to see?

An explanation of the current state of accessibility of this API.

Do you have any supporting links, references, or citations?

No response

Do you have anything more you want to share?

No response

MDN metadata

Contributor guide

Tech stack
css
Domain
documentation
Issue type
documentation
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
1-3 hours
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
fresh
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic understanding of web accessibilityfamiliarity with MDN contribution guidelines
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
Investigate the current state of assistive technology support for the CSS Custom Highlight API. Refer to the CSSWG thread (https://github.com/w3c/csswg drafts/issues/6498) and any other relevant sources. Draft an accessibility section for the MDN page (files/en us/web/api/css custom highlight api/index.md) explaining the implications and the purpose of the 'type' attribute. Consider comparing with the accessibility section of the <mark> element.