299816 2025-09-29 12:40:52 -0700 [CSS ZOOM] Zoom evaluation-time flag causes double zoom on border-width with em units 2025-10-17 20:12:53 -0700 1 1 1 Unclassified WebKit CSS WebKit Nightly Build Unspecified Unspecified RESOLVED FIXED InRadar P2 Normal --- 1 taher_ali webkit-unassigned koivisto webkit-bug-importer oldest_to_newest 2146920 0 taher_ali 2025-09-29 12:40:52 -0700 After PR #51076 is merged, we need to investigate and fix failures in tests such as: LayoutTests/fast/sub-pixel/zoomed-em-border.html The flag introduced in the PR #51076 enables applying zoom at evaluation time instead of style-build time. The goal is to move zoom application from style building into layout/rendering, and the feature flag is meant to prevent zoom from being applied during style building to avoid double zooming. However, what currently happens is: - The em unit on border-width is being resolved against the computed font size rather than the specified size - The computed font size already includes the zoom factor - When zoom is applied again during evaluation time to the border-width, it causes double zooming To address this, I modified font size computation at style-build time in computedFontSizeFromSpecifiedSize. I skipped applying zoom if the evaluation-time flag was enabled. This fixes the double zoom issue for border-width with font-related units but a new problem gets introduced: text itself is no longer zoom-induced as expected. This breaks assumptions in other parts of the engine where the computed font size is expected to already include zoom. Could this change also break other assumptions that rely on zoomed computed font sizes? 2146921 1 webkit-bug-importer 2025-09-29 12:40:59 -0700 <rdar://problem/161590209> 2149830 2 vitor.roriz 2025-10-09 17:00:36 -0700 Pull request: https://github.com/WebKit/WebKit/pull/52094 2150745 3 taher_ali 2025-10-13 22:28:03 -0700 investigate: LayoutTests/svg/zoom/page/zoom-replaced-intrinsic-ratio-001.htm 2152288 4 ews-feeder 2025-10-17 20:12:51 -0700 Committed 301757@main (4082642c7f1c): <https://commits.webkit.org/301757@main> Reviewed commits have been landed. Closing PR #52094 and removing active labels.