Check a UI design against the Design-for-Developers DO/DON'T rulebook — use when asked to review, critique, lint, or sanity-check a design, component, CSS/tokens, or screenshot for concrete rule violations (contrast below 4.5:1, line-height too loose, button text under 14px, arbitrary spacing off the baseline, ALL-CAPS body, underlined links, same font for headers and body, oversized/wrapping headers, misused badges/toasts, weak hierarchy). Complements impeccable and design:design-critique by contributing this specific numeric rubric, not replacing their judgment.
Concrete design numbers and formulas for building UI — use when you need exact values for type scale / font sizes, line-height, letter-spacing, spacing and grid systems, color weight ladders (50–950), color harmony (triadic/analogous/complementary), OKLCH palette generation, contrast/WCAG ratios, shadow depth values, button/badge/card/input padding and sizing, or visual-hierarchy levers. Pulls precise tokens so designs use intentional, consistent values instead of guessed ones. Pairs with impeccable and frontend-design when implementing interfaces.