[BUG] Claude Desktop sidebar rendering bug - white/black overlay blocks content on macOS

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?

A white/black overlay block appears on the left sidebar of Claude Desktop. The block is white during day mode and black during night mode (following system theme). When I resize the sidebar, the block extends with it. This blocks significant content on the left side and affects usability.

What Should Happen?

The sidebar should display normally without any overlay blocks. All interface content should be fully visible and accessible. When resizing the sidebar, no white or black blocks should appear.

Error Messages/Logs

Steps to Reproduce

Steps to Reproduce:
Open Claude Desktop on macOS Sequoia 15.7.3
Observe the left sidebar - a white block (in day mode) or black block (in night mode) appears overlaying content
Try resizing the sidebar by dragging its edge
Notice the overlay block extends/moves with the sidebar resize
Switch between light and dark system appearance modes
Observe the block changes from white to black accordingly
Additional context:
Issue persists after uninstalling/reinstalling the app
Issue persists after restarting computer
Issue persists after clearing cache and resetting app data
MacBook Pro 13-inch 2020, Intel Iris Plus Graphics 645, 8GB RAM

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

Claude 1.3883.0 (93ff6c) 2026-04-21T17:24:01.000Z

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_