[BUG] Chat window jitters/bounces vertically during conversation (in phpstorm)

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?

The chat interface rapidly jumps up and down (jitters) during a conversation. The scrolling becomes unstable and the content visibly shakes, making it hard to read.

Environment:

OS: Windows 11 Pro 10.0.26300
Claude Code version: 2.1.276
Shell: bash
Steps to reproduce:

Actual behavior: The entire chat area rapidly bounces up and down

What Should Happen?

Expected behavior: Chat should remain stable without vertical jittering.

Error Messages/Logs

Steps to Reproduce

Start a conversation with multiple back-and-forth messages
Include messages with images/screenshots
Observe the chat window content jumping vertically

Claude Model

Opus

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.276

Platform

Anthropic API

Operating System

Windows

Terminal/Shell

Other

Additional Information

_No response_