It does not at the expense of correctness AIUI. That doesn't seem a
great trade-off?
-- Emilio
On 10/28/25 6:44 PM, Philip Jägenstedt wrote:
LGTM1
There is some discussion in https://github.com/mozilla/standards-
positions/issues/1302 <https://github.com/mozilla/standards-positions/
issues/1302> about whether this feature triggers more layouts, which it
does not IIUC. But if there is more feedback from Mozilla on this and
some changes are needed for Gecko to avoid extra layout work, we should
adjust the spec and implementation as needed.
On Thu, Oct 23, 2025 at 8:16 AM Morten Stenshorne <[email protected]
<mailto:[email protected]>> wrote:
*Contact emails*
[email protected] <mailto:[email protected]>
*Explainer*
/No information provided/
*Specification*
https://drafts.csswg.org/css-anchor-position-1/#anchor-position-size
<https://drafts.csswg.org/css-anchor-position-1/#anchor-position-size>
*Summary*
When an anchor-positioned element is tethered against an anchor that
has a transform (or is contained by something with a transform),
resolve anchor() and anchor-size() functions against the bounding
box of the transformed anchor.
*Blink component*
Blink>Layout <https://issues.chromium.org/issues?
q=customfield1222907:%22Blink%3ELayout%22>
*Web Feature ID*
anchor-positioning <https://webstatus.dev/features/anchor-positioning>
*Motivation*
https://drafts.csswg.org/css-anchor-position-1/#anchor-position-size
<https://drafts.csswg.org/css-anchor-position-1/#anchor-position-
size> says that transform effects on an anchor should affect the
anchor box, so that anchor-positioned elements may be positioned
with regards to where an anchor is on screen. This chimes well with
how scroll offsets are also taken into account. https://
drafts.csswg.org/css-anchor-position-1/#scroll <https://
drafts.csswg.org/css-anchor-position-1/#scroll> This behavior is
crucial for creating sophisticated UI effects where elements need to
remain logically connected while one of them is being transformed.
Consider a tooltip that points to a button. If the button rotates or
scales on hover, you want the tooltip to move along with it,
maintaining its relative position.
*Initial public proposal*
/No information provided/
*TAG review*
/No information provided/
*TAG review status*
Pending
*Risks*
*Interoperability and Compatibility*
/No information provided/
/Gecko/: No signal (https://github.com/mozilla/standards-positions/
issues/1302 <https://github.com/mozilla/standards-positions/
issues/1302>)
/WebKit/: No signal (https://github.com/WebKit/standards-positions/
issues/558 <https://github.com/WebKit/standards-positions/issues/558>)
/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 <https://
chromium.googlesource.com/chromium/src/+/main/docs/testing/
web_platform_tests.md>?*
Yes
https://wpt.fyi/results/css/css-anchor-position?
label=master&label=experimental&aligned <https://wpt.fyi/results/
css/css-anchor-position?label=master&label=experimental&aligned>
*Flag name on about://flags*
/No information provided/
*Finch feature name*
CSSAnchorWithTransforms
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
https://issues.chromium.org/issues/382294252 <https://
issues.chromium.org/issues/382294252>
*Estimated milestones*
Shipping on desktop 144
Shipping on Android 144
Shipping on WebView 144
*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/5201048700583936?
gate=5152239350054912 <https://chromestatus.com/
feature/5201048700583936?gate=5152239350054912>
*Links to previous Intent discussions*
Intent to Prototype: https://groups.google.com/a/chromium.org/d/
msgid/blink-dev/
CAKWZFm6cenwaNiH0YEpJae2n%3DfWz7O553%3D9fKSukBL_KhvUK0A%40mail.gmail.com
<https://groups.google.com/a/chromium.org/d/msgid/blink-dev/CAKWZFm6cenwaNiH0YEpJae2n%3DfWz7O553%3D9fKSukBL_KhvUK0A%40mail.gmail.com>
This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.
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