# SLP-6 — Adjacent type-scale steps differ by at least 1.10x; no flat hierarchy L2 · hybrid · Anti-slop **Fails when:** heading/subheading/body at nearly the same size ## Requirement Where a page sets a heading, a subheading, and body text, the sizes it actually uses must step apart far enough to read as a hierarchy. Two adjacent steps in the ramp a page uses must differ by at least the ratio in this control's title. A page whose heading, subheading, and body all land within a few per cent of each other has no hierarchy, only three paragraphs. The control governs the ramp a page *uses*, not the scale it draws from. TYP-3 governs which sizes are available; SLP-6 governs whether the page picked sizes far enough apart to be legible as levels. ## Rationale A flat ramp is the most common way a generated page loses its structure. Every level is present in the markup, so heading semantics and accessibility checks pass, but a reader scanning the page cannot tell a section title from a sentence. The failure is visual, not structural, which is why no heading-hierarchy check catches it. ## Why the threshold is 1.10x The threshold was 1.25x, and at that value this control contradicted TYP-3 wherever TYP-3 falls back to Tailwind's default scale. Seven of that scale's twelve adjacent pairs fall below 1.25x (72/60, 36/30, 24/20, 20/18, 18/16, 16/14, and 14/12), so a page on that scale could not satisfy both controls at once. This repository proved it: `.prose` runs 30/24/20/16px, making its h2 to h3 step 24/20 = 1.20x, which TYP-3 allows and a 1.25x floor would fail. 1.10x clears Tailwind's whole default scale. The tightest adjacent pair on it is 20px to 18px = 1.1111x, which sits above the floor with about 0.011 of headroom. That is deliberate but narrow: the threshold is close to the ceiling of what is safe, and it cannot rise without reopening the contradiction with TYP-3. ## Why this is hybrid **Rendered-check half.** The measurement only exists once the page is rendered: what matters is which sizes actually land adjacent in the visual hierarchy of a real page, and a source scan cannot know that. A class may be declared and never used, and a size may be inherited rather than declared. That half belongs to the rendered check layer and is planned in #155; no rule exists yet in `rendered-check.py`'s evaluation registry. **Judgment half.** Whether two sizes are adjacent *steps*, rather than two unrelated elements that happen to sit near one another, is a reading of the page's structure. The evaluator holds that call. ## Passes when - Heading, subheading, and body sizes on the page are separated by at least the control's ratio at every adjacent step. - The ramp reads as levels at a glance, without needing weight or colour to carry the distinction alone. ## Fails when - A heading and its subheading are within a few per cent of each other. - Body copy and a section heading are the same size, distinguished only by weight. - A page declares several heading levels that all render at one size. ## Evaluator guidance **Flag**: - Adjacent steps in the page's own ramp that fall below the control's ratio. - A page where hierarchy is carried entirely by weight or colour because the sizes are flat. **Do not flag**: - Two elements at the same size that are not adjacent steps in a hierarchy — a caption and a data-table cell, two sibling labels, two body paragraphs. - Deliberately equal sizes where the hierarchy is carried by position and grouping, with a recorded rationale — this is an L2 control with `waiver: rationale`. - A size for being on or off the product's scale (the one its `DESIGN.md` defines, else the codebase's, else Tailwind's default). Scale membership is TYP-3's call, and SLP-6 raises no off-scale finding. The ratio check still applies to the sizes the page uses, whatever the scale's source. A product whose scale steps 16, 17, and 18px meets TYP-3 with any of them, but a page that sets body, subheading, and heading at those three sizes fails SLP-6. Pick sizes further apart on the scale, or record the rationale waiver.