Input box gray background feels visually intrusive in dark/black terminal theme

Summary

After upgrading to Codex v0.139.0, the prompt input box in the TUI now appears with a gray background. In a terminal theme where the overall background is pure black, this gray input area stands out quite strongly and feels visually intrusive.

It would be nice if the input box background could either be removed, made transparent/black, or controlled through a configuration option or feature flag.

Current behavior

The main Codex TUI background is pure black, but the input box uses a gray filled background.

This creates a strong visual contrast:

• the rest of the interface blends well with the terminal theme
• the input box becomes a large gray block
• it feels inconsistent with the immersive dark terminal experience
• it draws too much attention even when idle

Screenshot:

<img width="1340" height="875" alt="Image" src="https://github.com/user-attachments/assets/7d004e6e-be56-4133-97c5-dab03778bb57" />

Expected behavior

Preferably, the input box should match the surrounding terminal background more closely, for example:

• no filled gray background
• transparent background
• pure black background in dark mode
• or a configurable style option

A flag/config option would also be fine, for example:

[tui]
input_box_background = "transparent"

or:

codex --no-input-box-background

The exact API does not matter much; the main request is to allow users to disable the gray input background when using a pure black terminal theme.

Why this matters

For users who prefer a minimal, immersive terminal UI, especially with a pure black background, the gray input box feels too prominent. It makes the TUI look less integrated with the terminal and can be distracting during long coding sessions.

Environment

• Codex version: v0.139.0
• Shell: PowerShell / pwsh
• Terminal: Windows Terminal
• Theme: pure black background
• OS: Windows

Suggested solution

Please consider one of the following:

1. make the input box background transparent by default in dark/black themes
2. reduce the contrast of the input box background
3. add a config option or flag to disable the filled input background
4. expose input box styling through the existing TUI/theme configuration, if available

Thanks!