How to Create and Sell Custom Codex Themes – A Step‑by‑Step Guide

The author discovered that some people are selling Codex UI skins for 199 CNY and realized that customizing Codex is easy because an open‑source project called Codex Dream Skin was just released on GitHub, quickly gaining thousands of stars.

The project lets you replace Codex’s default white‑on‑black interface with any design, including custom background images, color schemes, decorative elements, sidebars, input boxes, and suggestion cards. The author showcases several themes—beauty, “God of Wealth”, Hatsune Miku, and a “Kun” idol theme—each illustrated with screenshots.

All native controls (sidebar, input box, project selector) remain functional, so the skin is not just a static overlay.

Because the repository’s README contains many scripts and technical terms, beginners may find it daunting, so the author provides a simplified three‑step tutorial that can be followed by anyone.

Step 1: Install the skin. Open Codex and tell the AI, “Use this open‑source project to change Codex’s theme https://github.com/Fei-Away/Codex-Dream-Skin”. The AI clones the repo, checks the Node.js version and OS, then runs the installation script. After installation the AI runs the default theme to verify the environment and shows the UI with the new skin applied.

使用这个开源项目，帮我更换 Codex 的主题 https://github.com/Fei-Away/Codex-Dream-Skin

Step 2: Generate personalized assets. The author asks the AI, “Generate a Naruto Uchiha Sasuke background and additional custom element images for full replacement.” GPT‑5.6 creates a full set of assets—including a widescreen Sasuke‑with‑Susano‑o background, a transparent Uchiha crest, sidebar patterns, lightning ornaments, and a kaleidoscopic Sharingan—and automatically applies them to Codex.

帮我生成火影忍者宇智波佐助的背景图，以及脚本支持的一些额外的定制元素图片，我要进行全方位的替换。

Step 3: Fine‑tune the result. If some text colors are hard to read on a dark background, the author simply tells the AI, “Some text colors look wrong,” and the AI adjusts the CSS accordingly.

好像还有些文字显示的配色是有问题的

The entire workflow requires almost no manual coding—just conversational prompts—but it can be slow because most of the time is spent waiting for the AI to generate images and adjust colors.

How the skin works. Codex is an Electron desktop application whose UI is rendered with web technologies. The project injects custom CSS and JavaScript via the Chrome DevTools Protocol (CDP) on the local loopback address (127.0.0.1). This injection happens entirely on the user’s machine, does not involve external network traffic, and does not modify the official .app package or its code‑signing. A provided Restore script can revert the changes with a single command, leaving future updates unaffected.