[css-values][css-fonts] Make the set of properties referred to as "font-*" more clear

@tabatkins

In the definition of font-relative units there is the text:

When used in the value of any 'font-*' property on the element they refer to...

Rather than leaving it to chance that the set of properties this refers to are the right set and all font effecting properties have the prefix font- and there are no non-font effecting properties that have the prefix font-, it would be clearer if this linked to either a complete list of properties or some other definition.

I believe the intent is that it is any property that might influence one of the font's metrics used by font-relative units. One option would be for CSS Fonts could define that concept and this could link to it.

cc @tabatkins @fantasai @svgeesus

An example of a property that I think probably belongs in the font-* group but doesn't have the font- prefix is math-depth, as it can effect the computed value of font-size.

That is a very good point, as I did not realize that property existed or had such an effect!

Checking my own understanding here.

In Fonts 4:

The 'font' longhands are all font-affecting
So are the 'font-synthesis' longhands, I think? Assuming that, say, synthetic bold might adjust the ch width or something.
Are the font-feature properties? Hmm, I guess they can affect which glyph is used for 0, and thus the ch width too. font-variant-east-asian could affect ic, too. And I guess the generic font-variant can affect both of them in theory.
I guess font-optical-sizing is too?
And font-language-override, as it could affect the glyph used for ic.
font-variant-emoji is not font-affecting, the affected characters aren't relied on by font-relative lengths nor are we likely to add font-relative lengths that are in the future reliant on those characters (or we can define them to be equal to the image variant, if we ever want to expose an emoji-width unit)
Nor is font-palette, as it's just colors

Fonts 5 doesn't introduce any relevant new properties.

MathML will need to define that math-depth is font-affecting.

And that's it, maybe?

[css-fonts-4][css-values-4] Define 'font-affecting properties' and li…

Also, better name suggestions than "font-affecting properties"?

font-* properties should use the metrics of the parent element's font…

@weinig

@weinig does this new subsection 1.2. Interaction With Font-Relative Units resolve this issue?

Closed by 4f50f67

@tabatkins

@tabatkins @svgeesus I think that definition may be overly broad.

Previously, it was decided that relative font units would be calculated in the absence of shaping - #5498, so I think any property that only effects shaping should be excluded.

Additionally, line-height should be excluded, as CSS Values explicitly calls out that it can depend on font-relative units of the element itself.

One additional property that needs exploring is zoom. I have filed #14260 on that particular issue.

font-variant-emoji is not font-affecting

Then you need to exclude it, because it is a longhand of font

@weinig

Okay, did a number of fixes that I tagged against #14396.

@weinig or @svgeesus : which properties just affect shaping?

Navigation Menu

Repository navigation

[css-values][css-fonts] Make the set of properties referred to as "font-*" more clear #14306

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

[css-values][css-fonts] Make the set of properties referred to as "font-*" more clear #14306

Description

Activity

weinig commented on Aug 11, 2026

tabatkins commented on Aug 11, 2026

tabatkins commented on Aug 11, 2026

tabatkins commented on Aug 11, 2026

svgeesus commented on Aug 18, 2026

svgeesus commented on Aug 25, 2026

weinig commented on Aug 27, 2026

Loirooriol commented on Aug 28, 2026

tabatkins commented on Sep 11, 2026

Metadata

Metadata

Assignees

Labels

Type

Projects

Milestone

Relationships

Development

Issue actions