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Computed Heading Level #1412
Description
Description
The headingoffset and headingreset attributes lets you increase the level of descendant headings within that element, allowing you to adjust the headings of an HTML include (e.g. converted from markdown). A :heading() CSS selector allows for targeting computed headings.
Allowing the heading algorithm to work with externally included content is expected to improve the a11y properties of the web.
Specification
https://html.spec.whatwg.org/#heading-levels-&-offsets
web-feature
heading-offset
Test Links
- https://wpt.fyi/results/html/rendering/sections?label=master&label=experimental&aligned
- https://wpt.fyi/results/html/semantics/sections?label=master&label=experimental&aligned
- https://wpt.fyi/results/css/selectors/heading.html?label=experimental&label=master&aligned
Additional Signals
No response
Activity
github-actions commentedon Sep 18, 2026
This comment was automatically generated based on the information you provided. Please don't edit it.
Below is additional information about the web feature (from the web-features project) which is referenced in your proposal.
If this doesn't accurately correspond to your proposal, please update your initial comment to include
web-features: <feature-id>.To find feature IDs, use the web-features explorer.
Feature Heading offset
headingoffsetHTML attribute offsets the heading level of descendant<h1>–<h6>elements. TheheadingresetHTML attribute prevents heading offset computation from traversing beyond the element.headingoffsetHTML global attribute,headingresetHTML global attributejamesnw commentedon Sep 18, 2026
Does this duplicate #1365?
gsnedders commentedon Sep 18, 2026
Thus, presumably, also the
heading-selectorsWeb Feature, and the https://drafts.csswg.org/selectors-5/#headings spec?mfreed7 commentedon Sep 25, 2026
+1. And while this one came last, it seems more complete, since it mentions
headingresetalso.