fix: prevent sidebar resize handle from overlapping file explorer buttons

[maxkoretskyi]

📝 Summary

Closes #5920

Description of Changes

The sidebar resize handle's hit area overlapped with the file explorer's three-dot menu button, making it difficult to click "Rename" and other file actions.

Two changes in frontend/src/components/editor/chrome/wrapper/app-chrome.tsx:

1. Removed mr-[-4px] negative margin on the sidebar panel body. This margin was pushing the file list content 4px into the resize handle zone, causing the entire handle to sit on top of interactive elements.

2. Reduced hitAreaMargins on PanelResizeHandle from the library default of { coarse: 15, fine: 5 } to { coarse: 15, fine: 2 }. The fine value controls the invisible hit area for mouse pointers — reducing it from 5px to 2px keeps the resize cursor from appearing too far from the actual panel edge. The coarse value (touch devices) is kept at the default since larger touch targets are needed there.

Checklist

• I have read the contributor guidelines.
• For large changes, or changes that affect the public API: this change was discussed or approved through an issue, on Discord, or the community discussions (Please provide a link if applicable).
• Tests have been added for the changes made.
• Documentation has been updated where applicable, including docstrings for API changes.
• Pull request title is a good summary of the changes - it will be used in the release notes.

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Project	Deployment	Actions	Updated (UTC)
marimo-docs	Ready	Preview, Comment	Feb 7, 2026 4:31pm