Brand accessibility

Status: Accepted

The contrast table below is generated from tokens.json by scripts/gen_contrast.py — edit the tokens, not the table. just generated rewrites it and refuses a hand edit. The prose around it is written by hand.

Whether the palette meets WCAG AA is a computed property of the tokens, not an opinion. This page states the baseline, with the actual ratios, and the pairings that are unsafe.

Consistent with P3: the contrast is measured, and re-measured by a CI check (ARCH-R40), not assumed.

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The measured baseline

Every number below is computed from tokens.json by gen_contrast.py, and the integrity job fails if the page and the tokens disagree. Nobody types a ratio here, because the page’s own premise is that a ratio is not an opinion — and because the numbers that were typed here went wrong three times over without anyone noticing.

AA needs 4.5:1 for body text and 3:1 for large text; AAA needs 7:1. The three surfaces are the grounds anything is ever set on: paper is the default, canvas the darker page behind cards, ink the dark theme.

tokens.json here is a distribution copy. The brand maintains it, and shared/assets.sha256 holds this copy byte-identical to it — so a token changing in the brand reaches this page by the copy being refreshed, and the table follows on the next run.

What the measurements decide

The body-safe set is whatever the table says it is. A pairing at AA or better may carry body text; one below it may not, and this page keeps no list beside the table. That is the whole of DES-R15: a list is a second statement of the table, and a second statement is the half that goes stale.

Both surfaces are measured, not just the default. A pairing is about a foreground and a ground, and the same token can clear AA on paper and fail on canvas, which is darker. The table carries a column for each so the question cannot be answered for the wrong one.

Amber is never text on a light ground, and the rule and the meter agree. fiber and fiber-light both fail against paper and canvas, which is the accessibility reason behind the brand rule that amber is signal-only. They clear AA against ink, and that is not a loophole — it is the same finding read from the other side, and it is why the dark theme lightens amber rather than keeping the light-theme value. Amber is fine as a non-text accent anywhere — a fibre core, a focus ring, an active underline — where contrast rules for text do not apply.

text-faint is restrained by emphasis, not by contrast. It clears AA for body text against paper and canvas both. It is still not body copy: it is the lowest-emphasis token in the palette, for eyebrow labels and secondary type, and information a reader needs does not go there. That is a typographic decision rather than a measured one, and saying so is better than implying a meter forbids it.

The dark theme is the comfortable one. The On ink column is generous throughout, which is why the ink theme lightens amber to fiber-light (token contract) — on a dark surface the lighter amber is legible where the same lightening on paper would fail. The theme switch is a contrast decision, not just a mood one.

The contract this creates

The design-token contract requires every body-text pairing to meet AA. Two checks, in two repositories, and neither is a person reading a table: brand:scripts/check_tokens.py fails a token change under which ink, ink-soft, text-muted, leaf or fiber-deep falls below AA on paper, and the integrity job here refuses a page that has drifted from the tokens. The brand check reads that list of five and paper alone; canvas, the ink theme and text-faint are measured in the table above and by nothing in CI.

A new or changed token that would put a failing pairing into body use is a contract violation, not a design preference.

Beyond contrast

Contrast is the measurable part; the web accessibility requirements still apply on top — focus visibility, keyboard operability, reduced-motion, text alternatives for the logo. The brand doesn’t override G3; it must satisfy it.

The logo in particular carries a text alternative (alt="lemonfiber"), and the ink/paper theme honours prefers-color-scheme and the explicit toggle (G3-R5, the token theme attribute).

Requirements

Related

• design-tokens contract — the CI check that enforces this
• brand-rules.md — the amber rule this explains
• G3 Accessibility — the broader requirements