VS Code Codex extension: Diff view styles make added and removed lines visually unclear

What version of Codex is running?

codex extension v0.4.62

What subscription do you have?

Plus

Which model were you using?

gpt-5.2

What platform is your computer?

Darwin 24.6.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

_No response_

What issue are you seeing?

The diff view styling makes it hard to understand what lines were actually changed.
• Added and removed lines visually overlap or look too similar
• Line highlighting does not clearly communicate what is new vs deleted
• Line numbers feel inconsistent and add to the confusion
• Overall, the diff looks visually broken, even when the change is small

Because of this, the diff is harder to read than before and requires extra effort to understand.

<img width="371" height="711" alt="Image" src="https://github.com/user-attachments/assets/b1046fba-4a3d-48eb-82af-5d4fd8388273" />

What steps can reproduce the bug?

1. Open any file with a small change (add/remove 1–3 lines).
2. View the changes in the diff view.
3. Compare how added and removed lines are styled.
4. Notice that the visual distinction between them is unclear.

What is the expected behavior?

• Added and removed lines should be clearly distinguishable by style and color
• No visual overlap between deleted and added lines
• Line numbers should be consistent and readable
• Diff view should be instantly readable, as it was before

Additional information

_No response_