76 tokens: the values everything else derives from
Nucleus's six themes and three density modes come from the same 76 tokens, nothing is a one-off override.
A theme is a token substitution, not a new stylesheet
Nucleus ships six themes (Default, Ocean, Forest, Rose, Amber, Mono) and three density modes (Comfortable, Compact, Spacious). None of them is a separate stylesheet, each is the same 76 tokens with different values, which is why switching one in the live playground updates every component at once without a class name changing anywhere.
That constraint is what keeps the count at 76 instead of growing every time someone wants a new look. A new theme is a new set of token values, not a new set of classes to document, validate, and keep in sync with the rest.
What actually gets tokenized
Color, spacing, radius, motion, and type scale: the five categories that touch nearly every component. Anything that would otherwise be a magic number in a component's CSS is a token reference instead, so a density change (Compact vs. Spacious) is one variable, not a search-and-replace across the framework.