It is recommended to use base and contrast followed by primary, secondary, tertiary, and so on as the color slug and name. Example: Your background color: "slug": "base", "color": "#ffffff", "name": "Base" Your foreground color: "slug": "contrast", "color": "#111111", "name": "Contrast" If more themes use this naming convention, it will be easier for the user to change themes and keep the color contrast and readability of their existing content. You can follow the discussion about best practices and the naming convention in this overview issue on GitHub: Default Colors, Theme Colors, and Custom Colors.