Re: [csswg-drafts] [css-anchor-position-1] `::placeholder` being an acceptable anchor exposes UA implementation details (#12949)

The CSS Working Group just discussed ``[css-anchor-position-1] `::placeholder` being an acceptable anchor exposes UA implementation details``, and agreed to the following:

* `RESOLVED: Only fully-styleable tree-abiding pseudo-elements (which doesn't include ::placeholder / ::marker) are acceptable anchors`

<details><summary>The full IRC log of that discussion</summary>
&lt;emilio> TabAtkins: currently the spec defines that any tree-abiding pseudos are an acceptable anchor<br>
&lt;emilio> ... this includes placeholder because that's tree-abiding, lives inside the `&lt;input>`.<br>
&lt;emilio> ... but that expose impl details of `&lt;input type=text>`<br>
&lt;emilio> ... if the user starts typing does that destroy the placeholder?<br>
&lt;emilio> ... the conclusion of the text is that anchoring to a placeholder doesn't seem useful<br>
&lt;emilio> ... so we'd be fine to exclude them from the acceptable anchors<br>
&lt;emilio> ... luke says it might be useful to do that with appearance: base because then it's strictly defined<br>
&lt;emilio> emilio: is it?<br>
&lt;emilio> TabAtkins: it should<br>
&lt;emilio> ... but luke also said that if it's too weird he'd be fine with dropping it<br>
&lt;emilio> ... so proposal is to remove ::placeholder from the list of acceptable anchor pseudos<br>
&lt;emilio> fantasai: do we need marker as well<br>
&lt;emilio> TabAtkins: I don't think we need to exclude marker, whether it exists is clear?<br>
&lt;emilio> fantasai: its positioning is not well defined<br>
&lt;emilio> TabAtkins: you can put a background<br>
&lt;emilio> fantasai: I think the spec should say fully stylable tree-abiding pseudo-elements<br>
&lt;emilio> PROPOSED: Only fully-styleable tree-abiding pseudo-elements (which doesn't include ::placeholder / ::marker) are acceptable anchors<br>
&lt;emilio> RESOLVED: Only fully-styleable tree-abiding pseudo-elements (which doesn't include ::placeholder / ::marker) are acceptable anchors<br>
&lt;astearns> I worry a bit there may be (or will be) restrictions to styling that would still accommodate anchor positioning<br>
&lt;TabAtkins> (me too)<br>
</details>


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Received on Thursday, 2 April 2026 22:09:38 UTC