Replaced 27 rendered font sizes whose nearest neighbours were 0.6% apart with a six‑step Major Third scale, and wrote the linter that fails the twenty‑eighth.

Situation. A measurement of the site’s rendered text found twenty‑seven distinct font sizes in use. Several were separated by less than one per cent — five values between 0.8 and 0.85 of the body size were all live at once, which is a difference no reader can perceive and every future editor will add to. Two of the headings were not sized by the stylesheet at all and were falling through to the browser’s own defaults, a ratio of 1.33 that matched nothing else on the page.

Task. The sizes had to become a scale with a stated ratio, and something had to prevent the twenty‑eighth.

Action. The scale is a Major Third, ratio 1.25, six named steps from fine print to display, each a token rather than a value. Headings are mapped explicitly onto steps instead of inheriting whatever the browser thinks, which is what fixed the two that had no size of their own. Only the bottom step is floored, so fine print stays legible on a phone without the whole scale being pinned. Logotypes are exempt by name rather than by accident. The linter is the part that makes it hold: it renders the site and fails on the twenty‑eighth distinct size. It has already earned its place twice — it caught a heading arriving at 1.17 of the body size, which is not a step of anything, and named the ratio in the failure message; and it caught inline code at 0.9, which is precisely the kind of value the scale exists to prevent. Alongside the scale went a measure of about seventy‑two characters, replacing an inherited fixed width that produced ninety‑one characters on a review page and a hundred and ten on the contact page.

Result. Six sizes where there were twenty‑seven, with a stated ratio, a stated measure and a check that refuses the next unplanned value. The constraint is real and occasionally inconvenient: a design that wants a size between two steps has to move to a step or argue for changing the scale, and that argument has been had and lost more than once.