[BUG] Korean/Japanese IME candidate window displays vertically instead of horizontally in Claude in Chrome extension

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?

When typing Korean or Japanese using an IME in the Claude in Chrome extension input field, the IME candidate window (suggestion popup) appears vertically (top-to-bottom) instead of horizontally (left-to-right) as expected.

This makes it difficult to select the correct character/word from the candidate list, as the layout is rotated 90 degrees from the standard IME behavior.

What Should Happen?

The IME candidate window should appear horizontally, following the cursor position inline, as is standard behavior in other input fields and applications.

Error Messages/Logs

Steps to Reproduce

1. Open Claude in Chrome extension
2. Focus on the chat input field
3. Switch system input method to Korean (한국어)
4. Start typing Korean or Japanese characters and trigger the IME candidate window
5. Observe that the IME candidate window appears vertically (top-to-bottom) instead of horizontally

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.1.59

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

The IME candidate window layout appears to be rendered vertically instead of horizontally. This may be related to how the extension handles the input field positioning or CSS writing-mode properties affecting the IME candidate popup display.

Reproducible with both Korean and Japanese IME on macOS.

OS: macOS
Terminal/Shell: Terminal.app (macOS)