Neo Zed themes are JSON files compatible with the upstream Zed format. You can edit files in ~/.config/zed/themes/ directly, or start from one of the bundled themes and iterate.
A theme defines colors for the editor surface, syntax highlighting, terminal palette, and UI chrome. Each color is a plain hex string, so it is easy to share a theme as a gist or a Git repository.
An in-browser theme builder with live preview is planned. Until then, see the documentation for the theme schema and a worked example.