Intent to Ship: Allow optional rounding parameter for `polygon()`

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Chromestatus

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May 26, 2026, 11:33:40 PM (3 days ago) May 26
to blin...@chromium.org, cg...@chromium.org
Contact emails
cg...@chromium.org

Specification
https://drafts.csswg.org/css-shapes-1/#funcdef-basic-shape-polygon

Summary
Allows an optional corner-rounding parameter in the polygon() CSS shape function. Developers can specify a length value to round polygon corners without manually computing bezier curves. Interactive demo: https://codepen.io/yisi/pen/NPRLEQN CSSWG issue: https://github.com/w3c/csswg-drafts/issues/9843

Blink component
Blink>CSS

Web Feature ID
shape-function

Motivation
Rounded polygons are a common design pattern on the web. Without this feature, developers who want rounded corners on a polygon shape must manually compute bezier control points or use workarounds such as SVG clip paths. The polygon() round parameter makes this directly expressible in CSS, reducing complexity and improving maintainability.

Initial public proposal
No information provided

TAG review
No information provided

TAG review status
Not applicable

Goals for experimentation
None

Risks


Interoperability and Compatibility
No information provided

Gecko: No signal (https://github.com/mozilla/standards-positions/issues/1197)

WebKit: No signal (https://github.com/WebKit/standards-positions/issues/474)

Web developers: No signals

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


Flag name on about://flags
No information provided

Finch feature name
CSSPolygonRounding

Rollout plan
Will ship enabled for all users

Requires code in //chrome?
False

Tracking bug
https://issues.chromium.org/issues/329302249

Estimated milestones
Shipping on desktop150
Shipping on Android150
Shipping on WebView150


Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

No information provided

Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/6636392944893952?gate=6487513336250368

This intent message was generated by Chrome Platform Status.

Mike Taylor

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May 27, 2026, 9:21:19 AM (2 days ago) May 27
to Jason Leo, blink-dev

On 5/26/26 11:33 p.m., Chromestatus wrote:

Contact emails
cg...@chromium.org

Specification
https://drafts.csswg.org/css-shapes-1/#funcdef-basic-shape-polygon

Summary
Allows an optional corner-rounding parameter in the polygon() CSS shape function. Developers can specify a length value to round polygon corners without manually computing bezier curves. Interactive demo: https://codepen.io/yisi/pen/NPRLEQN CSSWG issue: https://github.com/w3c/csswg-drafts/issues/9843

Blink component
Blink>CSS

Web Feature ID
shape-function

Motivation
Rounded polygons are a common design pattern on the web. Without this feature, developers who want rounded corners on a polygon shape must manually compute bezier control points or use workarounds such as SVG clip paths. The polygon() round parameter makes this directly expressible in CSS, reducing complexity and improving maintainability.

Initial public proposal
No information provided

TAG review
No information provided
Did TAG ever look at this?
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Mike Taylor

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May 27, 2026, 9:25:39 AM (2 days ago) May 27
to Jason Leo, blink-dev
Could you also please link to WPTs here?

Yoav Weiss (@Shopify)

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May 27, 2026, 11:25:47 AM (2 days ago) May 27
to blink-dev, Mike Taylor, blink-dev, Jason Leo
LGTM1



Flag name on about://flags
No information provided

Finch feature name
CSSPolygonRounding

Rollout plan
Will ship enabled for all users

Requires code in //chrome?
False

Tracking bug
https://issues.chromium.org/issues/329302249

Estimated milestones
Shipping on desktop 150 Shipping on Android 150 Shipping on WebView 150

Anticipated spec changes

Open questions about a feature may be a source of future web compat or interop issues. Please list open issues (e.g. links to known github issues in the project for the feature specification) whose resolution may introduce web compat/interop risk (e.g., changing to naming or structure of the API in a non-backward-compatible way).

No information provided

Link to entry on the Chrome Platform Status
https://chromestatus.com/feature/6636392944893952?gate=6487513336250368

This intent message was generated by Chrome Platform Status.
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Chris Harrelson

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May 27, 2026, 11:28:24 AM (2 days ago) May 27
to Yoav Weiss (@Shopify), blink-dev, Mike Taylor, Jason Leo
LGTM2

I've added the WPT test link to the chromestatus entry for you; please fill that in next time, thanks.

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Vladimir Levin

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May 27, 2026, 11:28:35 AM (2 days ago) May 27
to blink-dev, Chris Harrelson, blink-dev, Mike Taylor, Jason Leo, Yoav Weiss
LGTM3

To view this discussion visit https://groups.google.com/a/chromium.org/d/msgid/blink-dev/dd8618a3-c7d2-44c9-b14d-6de1861d2bebn%40chromium.org.

Jeffrey Yasskin

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May 27, 2026, 11:31:02 AM (2 days ago) May 27
to Mike Taylor, Jason Leo, blink-dev
On Wed, May 27, 2026 at 6:21 AM Mike Taylor <mike...@chromium.org> wrote:

On 5/26/26 11:33 p.m., Chromestatus wrote:

Contact emails
cg...@chromium.org

Specification
https://drafts.csswg.org/css-shapes-1/#funcdef-basic-shape-polygon

Summary
Allows an optional corner-rounding parameter in the polygon() CSS shape function. Developers can specify a length value to round polygon corners without manually computing bezier curves. Interactive demo: https://codepen.io/yisi/pen/NPRLEQN CSSWG issue: https://github.com/w3c/csswg-drafts/issues/9843

Blink component
Blink>CSS

Web Feature ID
shape-function

Motivation
Rounded polygons are a common design pattern on the web. Without this feature, developers who want rounded corners on a polygon shape must manually compute bezier control points or use workarounds such as SVG clip paths. The polygon() round parameter makes this directly expressible in CSS, reducing complexity and improving maintainability.

Initial public proposal
No information provided

TAG review
No information provided
Did TAG ever look at this?

FWIW, the TAG has not looked at this (https://github.com/w3ctag/design-reviews/issues?q=is%3Aissue%20state%3Aclosed%20funcdef-basic-shape-polygon), but for such a small addition that's already been approved by the CSSWG, it's unlikely we'd have significant comments.

Jeffrey
 
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