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[css-inline-3] Is alignment-baseline missing the hanging value? #13327
Description
The dominant-baseline property has the following values:
auto | text-bottom | alphabetic | ideographic | middle | central | mathematical | hanging | text-top
And the alignment-baseline property has the following values:
baseline | text-bottom | alphabetic | ideographic | middle | central | mathematical | text-top
Besides auto and baseline, they're identical except alignment-baseline is missing hanging. I assume that it's meant to have it, especially since it was an accepted value in SVG 1.1 and it is not listed as having been removed in SVG 2.
I can submit a small PR to put the hanging value into alignment-baseline if this is the case.
Activity
SebastianZ commentedon Jan 18, 2026
It seems this discrepancy is already there since those properties got introduced in 107993a.
@fantasai Is this intentional or just an oversight?
Sebastian
SebastianZ commentedon Jan 19, 2026
If it's an oversight, we should probably move all the keywords (except
autoandbaseline) to a new data type and reference it in both properties to avoid future discrepancies between them.Sebastian
[css-inline-3] Unify dominant-baseline and alignment-baseline values. w…
kbhomes commentedon Feb 2, 2026
In case they are meant to be the same, I made a proposed edit to the css-inline-3 spec in my fork that follows @SebastianZ's suggestion in the previous comment. I pulled out the baseline metrics into a new type and used them in both
dominant-baselineandalignment-baseline; this is modeled after the existing<text-edge>type and associated language of theline-fit-edgeandtext-box-edgeproperties.I haven't submitted this for a PR yet since this issue isn't resolved, but I can publish one if that's what we align on. 🙂
SebastianZ commentedon Feb 5, 2026
@kbhomes I'd say just create the PR and I request an async resolution to accept it (unless @fantasai jumps in and merges it early.😄)
So, proposed resolution: Accept @kbhomes' PR, merging the keywords from
dominant-baselineandalignment-baseline(exceptautoandbaseline) and thus addinghangingtoalignment-baseline.Sebastian
SebastianZ commentedon Feb 5, 2026
Ah, and @kbhomes, please also add a note to the Changes section when creating the PR!
Sebastian
[css-inline-3] Unify dominant-baseline and alignment-baseline values. w…
kbhomes commentedon Feb 5, 2026
Thanks @SebastianZ! I've published the PR including the new bullet in the
Changessection. Got blocked by the IPR commitment check, I just created the W3C account and linked to my GitHub but I think a maintainer needs to re-run the validation?SebastianZ commentedon Feb 7, 2026
I already re-ran the validation, though to merge it you also have to join the CSSWG as a member. Or, depending on whether the missing
hangingvalue is seen as an oversight, the PR could also be marked as non-substantive.Sebastian
astearns commentedon Feb 9, 2026
The CSSWG will automatically accept this resolution one week from now if no objections are raised here. Anyone can add an emoji to this comment to express support. If you do not support this resolution, please add a new comment.
Proposed Resolution: Add
hangingtoalignment-baselineto matchdominant-baselineastearns commentedon Feb 16, 2026
RESOLVED: Add
hangingtoalignment-baselineto matchdominant-baseline3 remaining items
kbhomes commentedon Feb 16, 2026
FYI I'll be adding WPTs for this as part of the Firefox implementation of
dominant-baseline(bug 2015279) andalignment-baseline(bug 1403440).@SebastianZ Would we be able to move ahead with merging the spec edit as non-substantive? I tried to see if I could submit an IPR commitment, but it appears I can only join the CSSWG as either an invited expert (which I'm not) or as part of my employer's organization (which I can't since I'm not representing them in any of this work).
SebastianZ commentedon Feb 17, 2026
@astearns @svgeesus Is it ok to just merge the related PR #13456?
Sebastian
astearns commentedon Feb 17, 2026
There should be a way to provide an individual IPR commitment. I reset the bot - could you try again, @kbhomes?
kbhomes commentedon Feb 17, 2026
@astearns Hmm, I'm not seeing a way to do that. The IPR check details link says:
Clicking the join link takes me to the CSSWG page with the message:
The instructions link gives me details for the two options that don't work for me — Invited Expert or represent an organization.
svgeesus commentedon Feb 17, 2026
I just requested an individual IPR commitment
kbhomes commentedon Feb 17, 2026
@svgeesus Thanks! Got the request and signed the commitment. Will the IPR check in #13456 automatically update or does it need to be revalidated?
svgeesus commentedon Feb 17, 2026
Commitment received. However the IPR bot, on being asked to revalidate, now says
Sigh, sorry for the inconvenience.
[css-inline-3] Unify dominant-baseline and alignment-baseline values. #…
kbhomes commentedon May 28, 2026
My new WPTs for
alignment-baselinewere merged from Firefox a couple weeks back: web-platform-tests/wpt#59796. This includes testing for the newhangingvalue. With that and the spec change I did in #13456, I think this issue can be closed out.SebastianZ commentedon May 28, 2026
Then let's do that.😄
Thank you for your hard work related to this, @kbhomes!
Sebastian