[BUG] macOS Claude App Bug Report — Chat Pane Left Margin Blank Gap

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

*Date: April 18, 2026
Reporter:** Marco Papa

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Summary

The chat pane renders with an approximately 1-inch blank/dead zone on the left side. The gap appears consistently across all conversations. A hard refresh (Command-R) temporarily resolves the issue, but it recurs.

Environment

• Platform: macOS (Mac mini)
• App: Claude for macOS (desktop app)
• Claude.ai plan: Pro
• Display: Retina / default scaling

What Should Happen?

Expected Behavior

Chat pane should render with correct left alignment immediately, without requiring a manual refresh.

Error Messages/Logs

## Actual Behavior

A ~1-inch blank gap appears on the left edge of the chat pane on every conversation load. Command-R fixes it temporarily.

## Frequency

Every conversation, every session. Persistent across days.

## Notes

- The issue may be related to a CSS layout shift or cached WebView state causing the initial render to miscalculate the chat container's left padding/margin.
- Command-R (reload) fixes it temporarily, suggesting a stale cached asset or a race condition during initial render.

Steps to Reproduce

1. Open any conversation on macOS Claude App
2. Observe the left side of the chat message pane
3. Approximately 1 inch of horizontal space is blank/unused, pushing content to the right
4. Press Command-R to hard refresh — the gap disappears and layout renders correctly
5. The gap reappears on subsequent page loads or new conversations

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Opus 4.6

Platform

Other

Operating System

macOS

Terminal/Shell

Other

Additional Information

<img width="1353" height="1499" alt="Image" src="https://github.com/user-attachments/assets/a989a466-ca90-40de-8e73-ba9e432b498e" />