Which built-in theme this inherits from
OptionalCssURL to the CSS file with token overrides (omit for built-in themes)
OptionalDescriptionOptional description shown in theme picker
Unique identifier (e.g. 'light', 'dark', 'izzy-dark')
Whether this is a built-in theme (light/dark)
Human-readable display name (e.g. 'Light', 'Dark', 'Izzy Dark')
OptionalPreviewOptional preview swatch colors for a future theme picker UI
OptionalTokensDerived --mj-* token overrides. Populated for brand themes emitted from seeds; an alternative/companion to CssUrl for token-based application and for feeding the Theme Builder preview without a round-trip through CSS.
Defines a theme available in the application. Built-in themes (light/dark) have no CssUrl. Custom themes specify a BaseTheme to inherit from and a CssUrl with overrides.