62c3a5c918
The display list builder only categorized direct children into CSS paint-order buckets. Stacking-context elements nested inside normal-flow intermediaries (like <body>) rendered in document order instead of at the correct steps 2/7 per CSS 2.1 Appendix E. This caused elements with explicit z-index to paint incorrectly relative to siblings. Add a recursive tree walk (collect_stacking_participants) that collects stacking-context descendants from the entire subtree, tracking ancestor overflow:hidden clip rects. Hoisted elements render with preserved clips via render_with_ancestor_clips. Skip guards in render_layout_box_normal and render_non_inline_descendants prevent double-rendering. Scope is limited to stacking contexts (positioned + z-index) to avoid regressions with float paint ordering. Positioned-auto deep hoisting and stacking contexts inside floats are documented follow-ups. Promotes 4 WPT tests, demotes 1 (pre-existing step 3/5 limitation). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
945 B
945 B