Body

The six tokens on body that every other element inherits from.

base/body.css sets the six properties that everything else inherits. It is the shortest file in the layer and the one with the widest reach.

body {
  background-color: var(--color-background);
  color: var(--color-text);
  font-family: var(--font-family-text);
  font-size: var(--font-size-text, 1rem);
  font-weight: var(--font-weight-text, 400);
  line-height: var(--line-height-text, 1.5);
}

Token	Sets
`--color-background`	Page background
`--color-text`	Default text colour
`--font-family-text`	Body typeface
`--font-size-text`	Base font size, falls back to `1rem`
`--font-weight-text`	Base weight, falls back to `400`
`--line-height-text`	Base line-height, falls back to `1.5`

The last three carry a literal fallback on purpose. The upstream reset this package is based on sets line-height: 1.5 on body; here that rule is commented out and the value comes from a token instead, with the fallback preserving the original behaviour when the token is missing.

--color-background and --color-text are the two that the dark theme overlay swaps. Nothing in this file mentions a colour scheme: the theme redefines the semantic tokens and the body follows. See dark mode in design-tokens.

Overriding

@layer base {
  :root {
    --font-size-text: 1.125rem;
  }
}

Changing --font-size-text moves the whole document, because every em-based and inherited size in the layer is measured against it. To change only one element, set its own token instead.