Fix YAML output not displaying in playground editor#16719
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Primer CSS's `d-flex` class applies `display: flex !important`, which overrides the inline `style.display = 'none'` set by JavaScript. The placeholder remained visible (computed display: flex) even after compilation, pushing the YAML output below the visible area where it was clipped by `overflow: hidden`. Switch to toggling Primer's `d-none`/`d-flex` utility classes instead of setting inline display styles, matching the pattern already used by the error/warning banners. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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Pull request overview
This PR fixes a CSS specificity issue where the YAML output was not displaying in the playground editor after compilation. The root cause was that Primer CSS's d-flex class (which uses !important) was overriding the inline style.display = 'none' set by JavaScript on the placeholder div. The fix switches from inline style toggling to using Primer's d-none/d-flex utility classes, which also use !important and thus work correctly.
Changes:
- Modified display toggling for the output placeholder from inline styles to Primer utility classes
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Primer CSS's `d-flex` class applies `display: flex !important`, which overrides the inline `style.display = 'none'` set by JavaScript. The placeholder remained visible (computed display: flex) even after compilation, pushing the YAML output below the visible area where it was clipped by `overflow: hidden`. Switch to toggling Primer's `d-none`/`d-flex` utility classes instead of setting inline display styles, matching the pattern already used by the error/warning banners. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
This was referenced Feb 19, 2026
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Summary
d-flexclass appliesdisplay: flex !important, which overrides the inlinestyle.display = 'none'set by JavaScript after compilationflex) despite the inline style sayingnone, pushing the YAML CodeMirror output below the visible container area whereoverflow: hiddenclipped itd-none/d-flexutility classes (which also use!important) instead of inline display styles, matching the pattern already used by the error/warning bannersRoot cause
Introduced in #16710 (CodeMirror migration). The old textarea-based editor used a
<pre>element withoutd-flex, so inline display toggling worked fine. The new placeholder div hasd-flexfor centering, creating the specificity conflict.Test plan
getComputedStyle(placeholder).displayreturns"flex"when it should be"none"🤖 Generated with Claude Code