Quick answer
Change a Codex Desktop theme, import a custom pack, verify readability, and restore the default appearance.
Use the native picker first
For base colors and fonts, use Settings > Appearance. Preview the result in a real task containing prose, code, a diff, and input controls before sharing it.
Apply a downloaded visual theme
Copy the validated installation prompt to Codex or run the fixed-version CLI command. The CLI creates local backups; advanced themes use a loopback-only visual layer and leave the signed app untouched.
Verify and restore
Confirm the sidebar, composer, menus, task content, and keyboard focus remain native and usable. Run the included restore action if anything looks wrong after an update.
Compatibility note: Native Codex appearance controls and advanced visual image layers are different. Get Codex Theme labels the delivery path and never treats an experimental visual layer as an official Appearance feature.