* fix: remove border-radius from app-shell to eliminate rounded corners below title bar
macOS windows already clip content to the window's own rounded corners.
The CSS border-radius: 10px on .app-shell created a second, inner rounding
that was visible below the transparent title bar, causing a visual gap
between the macOS frame and app content. The inset box-shadow remains for
a clean 1px border.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
* design: add window-frame-fix.pen showing target state
Shows the corrected window frame appearance with macOS traffic lights,
clean 1px border separator, and content extending edge-to-edge with
no inner rounded corners.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>
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