They can be constants, but not always: a design token can mutate based on device, light/dark/high-contrast mode, viewport size, user preference, locale, brand, product, theme, etc. This mutation can happen at runtime or at build time depending on the use-case.
Examples:
- "primary button background color" may be different across light and dark mode
- "header height" can vary across small and large viewports
- "user avatar background" may be defined by the user themselves
- "brand primary" may change for re-usable UI components based on the brand they're used for
Examples: - "primary button background color" may be different across light and dark mode - "header height" can vary across small and large viewports - "user avatar background" may be defined by the user themselves - "brand primary" may change for re-usable UI components based on the brand they're used for