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<!DOCTYPE bugzilla SYSTEM "https://bugs.webkit.org/page.cgi?id=bugzilla.dtd">

<bugzilla version="5.0.4.1"
          urlbase="https://bugs.webkit.org/"
          
          maintainer="admin@webkit.org"
>

    <bug>
          <bug_id>300837</bug_id>
          
          <creation_ts>2025-10-15 15:07:47 -0700</creation_ts>
          <short_desc>[css-anchor-position-1] Enable scrollable overflow of scrollable containing blocks by default</short_desc>
          <delta_ts>2025-10-28 14:42:57 -0700</delta_ts>
          <reporter_accessible>1</reporter_accessible>
          <cclist_accessible>1</cclist_accessible>
          <classification_id>1</classification_id>
          <classification>Unclassified</classification>
          <product>WebKit</product>
          <component>Layout and Rendering</component>
          <version>WebKit Local Build</version>
          <rep_platform>Unspecified</rep_platform>
          <op_sys>Unspecified</op_sys>
          <bug_status>RESOLVED</bug_status>
          <resolution>FIXED</resolution>
          
          
          <bug_file_loc></bug_file_loc>
          <status_whiteboard></status_whiteboard>
          <keywords>InRadar</keywords>
          <priority>P2</priority>
          <bug_severity>Normal</bug_severity>
          <target_milestone>---</target_milestone>
          
          <blocked>291856</blocked>
          <everconfirmed>1</everconfirmed>
          <reporter name="fantasai">fantasai.bugs</reporter>
          <assigned_to name="fantasai">fantasai.bugs</assigned_to>
          <cc>arrow_actions.7g</cc>
    
    <cc>bfulgham</cc>
    
    <cc>kiet.ho</cc>
    
    <cc>simon.fraser</cc>
    
    <cc>webkit-bug-importer</cc>
    
    <cc>zalan</cc>
          

      

      

      

          <comment_sort_order>oldest_to_newest</comment_sort_order>  
          <long_desc isprivate="0" >
    <commentid>2151429</commentid>
    <comment_count>0</comment_count>
    <who name="fantasai">fantasai.bugs</who>
    <bug_when>2025-10-15 15:07:47 -0700</bug_when>
    <thetext>The default alignment safety for absolutely positioned boxes pulls them away from overflow the containing block edge. This is good in general, but when the containing block is a scroll container, it&apos;s safe to overflow into the scrollable overflow region.

Per CSSWG resolution, we should allow overflow into these regions rather than trying to strictly contain the abspos:
    https://github.com/w3c/csswg-drafts/issues/12106</thetext>
  </long_desc><long_desc isprivate="0" >
    <commentid>2151430</commentid>
    <comment_count>1</comment_count>
    <who name="Radar WebKit Bug Importer">webkit-bug-importer</who>
    <bug_when>2025-10-15 15:07:54 -0700</bug_when>
    <thetext>&lt;rdar://problem/162722820&gt;</thetext>
  </long_desc><long_desc isprivate="0" >
    <commentid>2152414</commentid>
    <comment_count>2</comment_count>
    <who name="Ehren">arrow_actions.7g</who>
    <bug_when>2025-10-19 03:22:22 -0700</bug_when>
    <thetext>Is this a duplicate of the following? https://bugs.webkit.org/show_bug.cgi?id=299950

If so, this has been fixed in Safari TP 230. If I&apos;ve misunderstood your bug report, then please ignore this!</thetext>
  </long_desc><long_desc isprivate="0" >
    <commentid>2154109</commentid>
    <comment_count>3</comment_count>
    <who name="fantasai">fantasai.bugs</who>
    <bug_when>2025-10-24 12:14:22 -0700</bug_when>
    <thetext>That was a quick fix just for the initial containing block to handle the most common broken case, this is a more general bug for a proper fix for the general case. :)</thetext>
  </long_desc><long_desc isprivate="0" >
    <commentid>2154117</commentid>
    <comment_count>4</comment_count>
    <who name="fantasai">fantasai.bugs</who>
    <bug_when>2025-10-24 12:33:17 -0700</bug_when>
    <thetext>Pull request: https://github.com/WebKit/WebKit/pull/52970</thetext>
  </long_desc><long_desc isprivate="0" >
    <commentid>2154119</commentid>
    <comment_count>5</comment_count>
    <who name="fantasai">fantasai.bugs</who>
    <bug_when>2025-10-24 12:41:28 -0700</bug_when>
    <thetext>There&apos;s also two things interacting here:
- What&apos;s the size of the containing block? This is https://bugs.webkit.org/show_bug.cgi?id=291864 which also needs to be fixed.
- What happens when we overflow the containing block. That&apos;s this bug.

Both of them mitigate situations where the box can overlap the anchor, but they are slightly different in their effects... this one is the easier one to fix. :)</thetext>
  </long_desc><long_desc isprivate="0" >
    <commentid>2154830</commentid>
    <comment_count>6</comment_count>
    <who name="EWS">ews-feeder</who>
    <bug_when>2025-10-28 14:42:55 -0700</bug_when>
    <thetext>Committed 302259@main (c16b70c96c64): &lt;https://commits.webkit.org/302259@main&gt;

Reviewed commits have been landed. Closing PR #52970 and removing active labels.</thetext>
  </long_desc>
      
      

    </bug>

</bugzilla>