Web-Facing Change PSA: CSS letter-spacing and word-spacing: percentage values

Chromestatus

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Oct 22, 2025, 10:59:47 AM (9 days ago) Oct 22

to blin...@chromium.org, jja0...@gmail.com

Contact emails

jja0...@gmail.com

Specification

https://www.w3.org/TR/css-text-4/#propdef-letter-spacing

Summary

Enables percentage values for the letter-spacing and word-spacing CSS property, as defined in the CSS Text Module Level 4 spec. Percentage values are calculated relative to the advance measure of the space character (U+0020). This gives developers more robust and flexible control over typography, particularly in responsive designs where text spacing needs to adapt to different viewports and font sizes.

Blink component

Blink>Layout>Inline

Web Feature ID

letter-spacing

Search tags

letter-spacing, word-spacing

Risks

Interoperability and Compatibility

Risks are low. This is a support for new value of CSS properties. So sites not using properties won't be affected. Firefox and Safari has supported this feature for years.

Gecko: Shipped/Shipping

WebKit: Shipped/Shipping (https://github.com/WebKit/WebKit/pull/18771)

Web developers: No signals (https://issues.chromium.org/issues/327740939) The issue has 3 votes.

Other signals:

WebView application risks

Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?

No information provided

Debuggability

No information provided

Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?

Yes

Is this feature fully tested by web-platform-tests?

Yes
- "letter-spacing-percentage-001.html" file in https://wpt.fyi/results/css/css-text/letter-spacing - "word-spacing-percentage-001.html" file in https://wpt.fyi/results/css/css-text/word-spacing

Tracking bug

https://issues.chromium.org/issues/327740939

Estimated milestones

Shipping on desktop	143
Shipping on Android	143
Shipping on WebView	143
Shipping on iOS	143

Link to entry on the Chrome Platform Status

https://chromestatus.com/feature/5074916059381760

This intent message was generated by Chrome Platform Status.

Chromestatus

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Oct 27, 2025, 11:17:52 PM (3 days ago) Oct 27

to blin...@chromium.org, jja0...@gmail.com

Shipping on desktop	145
Shipping on Android	145
Shipping on WebView	145
Shipping on iOS	145

Mike Taylor

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Oct 28, 2025, 12:56:21 AM (3 days ago) Oct 28

to 김민성, blink-dev

Given that we're adding support to a new type of value, an Intent to Ship is a better fit than a PSA (see Implementation of existing standard). Can you please resend? If that's confusing, feel free to reach out to me directly for help.

On 10/27/25 6:17 p.m., Chromestatus wrote:

Contact emails
jja0...@gmail.com

Specification
https://www.w3.org/TR/css-text-4/#propdef-letter-spacing

I assume https://www.w3.org/TR/css-text-4/#propdef-word-spacing is the other relevant spec reference, can we include that in the Intent to Ship?

Summary
Enables percentage values for the letter-spacing and word-spacing CSS property, as defined in the CSS Text Module Level 4 spec. Percentage values are calculated relative to the advance measure of the space character (U+0020). This gives developers more robust and flexible control over typography, particularly in responsive designs where text spacing needs to adapt to different viewports and font sizes.

Blink component
Blink>Layout>Inline

Web Feature ID
letter-spacing

Search tags
letter-spacing, word-spacing

Risks

Interoperability and Compatibility
Risks are low. This is a support for new value of CSS properties. So sites not using properties won't be affected. Firefox and Safari has supported this feature for years.

Gecko: Shipped/Shipping

I'm surprised that Firefox is failing so many tests at https://wpt.fyi/results/css/css-text/letter-spacing?label=experimental&label=master&aligned if they shipped this. Do you happen to know why?

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