Quick answer
Understand Codex base themes, accents, foreground and background colors, UI fonts, code fonts, and theme sharing.
Native appearance controls
Codex Desktop exposes a native appearance layer for base mode, accent, background and foreground colors, and UI and code fonts. Start there when you want the most update-resistant result.
Shareable themes
A shared native theme should preserve readable contrast across task content, code, diffs, menus, and composer controls. Test every exported theme on the current stable app before publishing it.
Where visual themes differ
Image backgrounds and decorative layout treatments go beyond the publicly described native controls. Treat them as a separate visual compatibility layer and always provide a restore path.
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.