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[css-align-3][css-anchor-position-1] Clarify that position-area normal alignment magic triggers overflow safety magic
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‎css-align-3/Overview.bs‎

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@@ -898,7 +898,7 @@ Content Distribution for Scroll Containers</h5>
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Self-Alignment for Absolutely Positioned Boxes</h5>
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For [=absolutely positioned=] [=alignment subjects=]
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whose relevant [=self-alignment property=] is not ''justify-self/normal'',
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whose relevant [=used value|used=] [=self-alignment property=] is not ''justify-self/normal'',
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the default [=overflow alignment=] behavior is as follows:
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<div algorithm="default overflow self-alignment for abspos">
@@ -2514,175 +2514,10 @@ Appendix A: Static Position Terminology</h2>
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<h2 id="changes">
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Changes</h2>
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Changes since the <a href="https://www.w3.org/TR/2023/WD-css-align-3-20230217/">17 February 2023 Working Draft</a> include:
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<ul>
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<li>Made [=block containers=] default to ''safe'' alignment.
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See [[#auto-safety-default]].
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(<a href="https://github.com/w3c/csswg-drafts/issues/8992">Issue 8992</a>)
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<li>Made [=absolutely positioned boxes=] default to using a “smart” safe alignment
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that allows unsafe overflow of the [=inset-modified containing block=]
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while maintaining safety within the [=original containing block=].
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See [[#auto-safety-position]].
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(<a href="https://github.com/w3c/csswg-drafts/issues/10316">Issue 10316</a>,
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<a href="https://github.com/w3c/csswg-drafts/issues/9960">Issue 9960</a>)
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<li>Make all the ''space-*'' keywords fallback to ''safe'' overflow.
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(<a href="https://github.com/w3c/csswg-drafts/issues/10154">Issue 10154</a>)
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<li>Clearly define the interaction of overflowing [=content distribution=] and [=scroll containers=]
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to not impact layout, but to only affect the extent of the [=scrollable overflow area=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/4957">Issue 4957</a>)
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<li>Only apply the special margin-edge baseline rule for [=scroll container=] [=block containers=]
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when 'baseline-source' is its [=initial value=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/8214">Issue 8214</a>)
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<li>When synthesizing the baseline of an orthogonal-flow box,
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make the assumed parallel [=writing mode=] sensitive to 'direction'.
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(<a href="https://github.com/w3c/csswg-drafts/issues/7775">Issue 7775</a>)
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<blockquote>
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<del><p>Otherwise,
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assume either ''horizontal-tb'' or ''vertical-lr'' 'writing-mode',
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whichever is orthogonal to the box’s own 'writing-mode'.</p></del>
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<ins><p>Otherwise:</p>
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<ul>
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<li>If the box’s own [=writing mode=] is vertical,
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assume ''horizontal-tb''.
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<li>If the box’s own [=writing mode=] is horizontal,
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assume ''vertical-lr'' if 'direction' is ''ltr''
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and ''vertical-rl'' if 'direction' is ''rtl''.
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</ul>
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</ins>
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</blockquote>
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<li>Clarify that spanning cells only participate in the first/last row they span
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when participating in first/last baseline alignment.
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(<a href="https://github.com/w3c/csswg-drafts/issues/7655">Issue 7655</a>)
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<li>Define the 'grid-gap' properties as [=legacy name aliases=] of the 'gap' properties.
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(<a href="https://github.com/w3c/csswg-drafts/issues/8014">Issue 8014</a>)
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<li>Defer definition of ''align-self/normal'' alignment for [=absolutely positioned boxes=] to [[css-position-3]].
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(<a href="https://github.com/w3c/csswg-drafts/issues/11215">Issue 11215</a>,
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<a href="https://github.com/w3c/csswg-drafts/issues/11285">Issue 11285</a>)
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<li>Changed sentence about applicability of 'row-gap' to [=multi-column containers=]
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to indicate that it applies in [[CSS-MULTICOL-2]].
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(<a href="https://github.com/w3c/csswg-drafts/issues/11539#issuecomment-2628431667">Issue 11539</a>)
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<li>Defined that [=gutters=] dissappear at [=fragmentation breaks=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/11520">Issue 11520</a>)
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2021/WD-css-align-3-20211224/">24 December 2021 Working Draft</a> include:
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<ul>
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<li>Define the baselines of a [=multi-column container=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/7856">Issue 7856</a>,
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<a href="https://github.com/w3c/csswg-drafts/issues/7639">Issue 7639</a>)
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<li>Use the [=writing mode=] of the [=static-position containing block=]
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when determining the [=static position=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/7599">Issue 7599</a>,
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<a href="https://github.com/w3c/csswg-drafts/issues/7612">Issue 7612</a>;
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<a href="https://github.com/w3c/csswg-drafts/commit/29e253d0344d4a2bec47305a70cbcbfde669af7b">Changes</a>)
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<li>Remove definition of special behavior for including padding in [=scrollable overflow=]
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for non-''align-content/normal'' alignments
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since this is now defined unconditionally in [[!CSS-OVERFLOW-3]].
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(<a href="https://github.com/w3c/csswg-drafts/issues/129#issuecomment-1113489051">Issue 129</a>)
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<li>Minor clarifications:
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* Define [=fallback alignment=] of a [=baseline-sharing group=]
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as the shared [=fallback alignment=] of its individual items.
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* Annotate <<length-percentage>> value definitions using [=CSS bracketed range notation=].
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2020/WD-css-align-3-20200421/">21 April 2020 Working Draft</a> include:
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<ul>
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<li>Allowed reordering of ''[ first | last ]'' and ''align-self/baseline'' components of <<baseline-position>>.
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(<a href="https://github.com/w3c/csswg-drafts/issues/5235">Issue 5235</a>)
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<li>Make [=fallback alignment=] of ''space-around'' and ''space-evenly'' include ''safe''.
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(<a href="https://github.com/w3c/csswg-drafts/issues/5088">Issue 5088</a>)
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<li>Various corrections to <css>normal</css> alignment and percentage gaps
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to match respective layout specs.
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<li>Corrections to special legacy handling of the [=last baseline set=] of [=scroll containers=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/3611">Issue 3611</a>)
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<li>Clarify that a box with no [=baseline set=] synthesizes its [=alignment baseline=] as needed.
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(<a href="https://github.com/w3c/csswg-drafts/issues/3611">Issue 3611</a>)
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<li>Clarified that only non-replaced boxes are affected by [=content distribution=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/4545">Issue 4545</a>)
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<li>Clarified when a box has a [=coordinated self-alignment preference=]
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that enables [=baseline content-alignment=],
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particularly with respect to ''margin/auto'' [=margins=].
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(<a href="https://github.com/w3c/csswg-drafts/issues/5923">Issue 5923</a>)
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<li>Better define how baseline self-alignment and content-alignment interact.
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(<a href="https://github.com/w3c/csswg-drafts/issues/6389">Issue 6389</a>)
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<li>Clarify how baseline-sharing groups determine their fallback alignment.
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(<a href="https://github.com/w3c/csswg-drafts/issues/7645">Issue 7645</a>)
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2018/WD-css-align-3-20181206/">6 December 2018 Working Draft</a> include:
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<ul>
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<li>Improved the center self-alignment of absolutely-positioned elements.
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<a href="https://github.com/w3c/csswg-drafts/issues/4659">Issue 4659</a>
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<li>Fixed inconsistent fallback of baseline alignment in mixed writing modes.
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<a href="https://github.com/w3c/csswg-drafts/issues/3454">Issue 3454</a>
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<li>Minor editorial fixes and clarifications.
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2018/WD-css-align-3-20180830/">30 August 2018 Working Draft</a> consist of some minor clarifications.
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Changes since the <a href="https://www.w3.org/TR/2018/WD-css-align-3-20180423/">23 April 2018 Working Draft</a> include:
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<ul>
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<li>Better definition of how the alignment properties interact with absolutely-positioned boxes with ''left/auto'' offsets.
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See [[#justify-abspos]], [[#align-abspos]], [[#abspos-sizing]], and [[#staticpos-rect]].
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<li>More detailed definition of how the <a>content-distribution properties</a> work on <a>scroll containers</a>.
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See [[#overflow-scroll-position]].
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<li>Noted CSS2’s special rules about the baselines of inline-block <a>scroll containers</a>.
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<li>Defined that percentage gaps compute against zero when calculating intrinsic sizes, and resolve during layout. (<a href="https://github.com/w3c/csswg-drafts/issues/509">Issue 509</a>)
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<li>Miscellaneous minor clarifications.
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2025/WD-css-align-3-20250311/">11 March 2025 Working Draft</a> include:
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* Clarify that [[#auto-safety-position]] applies when 'position-area' alters the [=used value=] of ''align-self/normal''.
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Changes since the <a href="https://www.w3.org/TR/2017/WD-css-align-3-20170906/">6 September 2017 Working Draft</a> include:
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<ul>
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<li>Added more illustrations! Many thanks to Melanie Richards for working through a difficult diagramming problem.
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<li>Fixed errors in property definition table of 'gap' shorthand.
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<li>Defining percentage gaps to resolve to zero when the containing block’s size depends on the gaps.
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(<a href="https://github.com/w3c/csswg-drafts/issues/509">Issue 509</a>,
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<a href="https://github.com/w3c/csswg-drafts/issues/2297">Issue 2297</a>)
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<li>Fixed errors in handling <css>left</css> and <css>right</css> in the grammars.
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<li>Fixed discrepancy in ''align-content/space-align'' fallback alignment.
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(<a href="https://github.com/w3c/csswg-drafts/issues/2316">Issue 2316</a>)
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<li>Tightened up handling of baseline alignment in cases where the box edges don't align.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1556">Issue 1556</a>,
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<a href="https://github.com/w3c/csswg-drafts/issues/1611">Issue 1611</a>)
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<li>Miscellaneous clarifications.
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2017/WD-css-align-3-20170720/#changes">20 July 2017 Working Draft</a> include:
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<ul>
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<li>Added the 'row-gap' and 'column-gap' properties and 'gap' shorthand,
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applying them to both <a>grid layout</a> and <a>flex layout</a>
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to replace the grid-specific 'grid-row-gap'/'grid-column-gap'/'grid-gap' properties.
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2017/WD-css-align-3-20170515/">15 May 2017 Working Draft</a> include:
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<ul>
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<li>Dropped the ''left'' and ''right'' keywords from 'align-self' and 'align-content'.
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They may be re-introduced in a later level if there is demand.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1403">Issue 1403</a>)
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<li>Assigned ''end'' fallback alignment to ''align-self/stretch'' cases when combined with ''last baseline'' content-alignment.
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<li>Disabled baseline alignment across cells in a table column,
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due to implementation complexity.
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<li>A large number of minor corrections and clarifications <a href="https://github.com/w3c/csswg-drafts/issues?q=is%3Aissue+label%3Acss-align-3+author%3Adbaron">reported by David Baron</a>.
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</ul>
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Changes since the <a href="https://www.w3.org/TR/2017/WD-css-align-3-20170407/">7 April 2017 Working Draft</a> include:
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<ul>
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<li>Adding a section to clarify handling of partial implementations.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1167">Issue 1167</a>)
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<li>Dropped <<baseline-position>> value of 'justify-content' since it can't do anything anyway.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1184">Issue 1184</a>)
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<li>Deferred ability to specify fallback alignments to Level 4.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1002#issuecomment-295143297">Issue 1002</a>)
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<li>Fixed position of <<overflow-position>> wrt <<content-position>>.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1001">Issue 1001</a>)
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<li>Fixed rules for handling baseline-aligned boxes being aligned along their block axis.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1038">Issue 1038</a>)
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<li>Renamed ''justify-items: auto'' to ''justify-items: legacy''.
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(<a href="https://github.com/w3c/csswg-drafts/issues/1318">Issue 1318</a>)
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<li>Clamped baselines of scrollable boxes to the border edge, rather than margin edge.
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(<a href="https://github.com/w3c/csswg-drafts/issues/766">Issue 766</a>)
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<li>Updated the flex container gap definition to use [=gutter=]. (<a href="https://github.com/w3c/csswg-drafts/issues/12084">Issue 12084</a>)
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</ul>
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See also <a href="https://www.w3.org/TR/2025/WD-css-align-3-20250311/#changes">previous changes</a>.
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<h2 id="privacy">
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Privacy Considerations</h2>

‎css-anchor-position-1/Overview.bs‎

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@@ -1222,7 +1222,7 @@ Anchor-Based Alignment {#alignment}
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Area-specific Default Alignment</h3>
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When 'position-area' is not ''position-area/none'',
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the behavior of the ''align-self/normal'' [=self-alignment=] value
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the [=used value=] of ''align-self/normal'' [=self-alignment=]
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changes depending on the <<position-area>> value,
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to align the box towards the anchor:
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