Re: [csswg-drafts] [css-align][css-position][css-anchor-position] Introduce "document containing block" for some purposes? (#10861)

The CSS Working Group just discussed `[css-align][css-position][css-anchor-position] Introduce "document containing block" for some purposes?`, and agreed to the following:

* `RESOLVED: All percentages (insets, sizes) resolve against the effective containing block (no inconsistency)`

<details><summary>The full IRC log of that discussion</summary>
&lt;fantasai> TabAtkins: If you have an abspos that has its CB generated by a scroller, right now, it's CB is like the ICB -- a viewport-sized box anchored to the origin<br>
&lt;fantasai> TabAtkins: This is not great in many case, so we had adopted a proposal to adopt a CB approximating the scrollable area<br>
&lt;fantasai> TabAtkins: Ian and I thought that percentages should still resolve against this new CB<br>
&lt;fantasai> TabAtkins: fantasai thought that was weird and inconsistent so thought we shouldn't do that, and be consistent<br>
&lt;fantasai> TabAtkins: Ian and I reviewed, and couldn't remember why we wanted width/height to resolve against the scrollport when the rest of the CB is the entire scrollable area<br>
&lt;fantasai> TabAtkins: So we're ok with resolving on all percentages resolving against the effective containing block<br>
&lt;fantasai> RESOLVED: All percentages (insets, sizes) resolve against the effective containing block (no inconsistency)<br>
</details>


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Received on Wednesday, 6 August 2025 16:24:50 UTC