/sota-frontend-design

name: sota-frontend-design
description: >
  State-of-the-art web design, UI/UX, and motion engineering standards (2026). Use when building
  OR auditing/reviewing user interfaces: components, pages, design systems, stylesheets, themes,
  forms, navigation, animations, or accessibility. Covers typography, color (OKLCH, dark mode),
  spacing/layout (grid, container queries, subgrid), design tokens and component APIs, UX patterns
  (forms, loading/empty/error states, destructive actions), WCAG 2.2 AA accessibility, motion
  design, and responsive/modern CSS. Trigger keywords: UI, UX, web design, CSS, component,
  accessibility, a11y, responsive, animation, motion design, design system, layout, typography,
  dark mode, design tokens, frontend review, WCAG.

SOTA Frontend Design

Purpose

Make every interface this agent builds — and every interface it reviews — meet 2026 state-of-the-art for visual craft, UX, accessibility, motion, and CSS architecture. The skill has two operating modes (BUILD and AUDIT) backed by seven rules files. WCAG 2.2 AA is the hard floor in both modes; distinctive, intentional design (not template/AI-generic output) is the quality bar. Rules are written for an expert reader: imperative, numeric, with good/bad pairs.

BUILD mode

When creating or modifying UI (components, pages, styles, animations):

1. **Lock the system before the screens.** Establish or locate the project's tokens first: type scale, color ramps (OKLCH, semantic layer), 4/8pt space scale, radius scale, depth language, duration/easing tokens. If a design system exists, conform to it — extend tokens rather than inlining values. Read [`rules/01`](rules/01-typography-and-color.md) + [`rules/03`](rules/03-design-systems-components.md) before writing the first stylesheet. 2. **Default stack:** semantic HTML → CSS grid/flex with `gap` → container queries for component responsiveness → logical properties → cascade layers. Headless library or native element (`<dialog>`, `popover`, `<details>`) for any interactive widget before hand-rolling. 3. **Build all states, not the happy path.** Every interactive component ships the 9-state contract (hover, focus-visible, active, disabled, loading, error, empty, skeleton + default); every data view ships loading/error/empty/partial/ideal (`rules/03 §4`, [`rules/04`](rules/04-ux-patterns.md)). 4. **Accessibility is built in, not bolted on:** labels, keyboard model per APG, focus management, live regions, contrast verified in both themes, `prefers-reduced-motion` honored from the first animation ([`rules/05`](rules/05-accessibility.md), `rules/06 §6`). 5. **Motion is purposeful:** every animation justifies itself as orientation, feedback, continuity, or status; transform/opacity only; durations 200–300ms enter / faster exit ([`rules/06`](rules/06-motion-design.md)). 6. **Be distinctive on purpose:** make ≥ 3 deliberate global design decisions (typeface with character, OKLCH accent, signature element) and apply the anti-generic kill list (`rules/07 §6`). Spend personality on marketing/empty surfaces; keep product surfaces calm. 7. **Self-check before finishing:** run the relevant rules-file audit checklists against your own output. Test mentally (or actually) at 320px, 200% zoom, keyboard-only, dark mode, RTL, and with worst-case content (long strings, 0 items, 10k items).

AUDIT mode

**Coverage:** every `rules/` file's Audit checklist applies in AUDIT mode. Mark one *not applicable* only with its reason in the report — never skip a file because the thing it checks for is absent, since that absence may be the finding.

When reviewing existing UI code, designs, or rendered pages:

1. **Scope pass:** identify surfaces (pages/components), the token/system layer (or its absence), and the framework. Grep for systemic smells first — they multiply findings: hex/px literals in components, `outline: none`, `transition: all`, `user-scalable=no`, placeholder-as-label, click-handler `<div>`s, `:focus` without `:focus-visible`, `will-change` in static CSS, physical properties (`margin-left`) in new code. 2. **Per-domain pass:** walk each rules file's "Audit checklist" section against the code. Prioritize [`rules/05`](rules/05-accessibility.md) (accessibility) — it carries legal weight — then [`rules/04`](rules/04-ux-patterns.md) (UX states), then visual/system/motion. 3. **Runtime verification where possible** (Playwright/browser): keyboard-only task completion, 320px reflow, 200% zoom, both themes, reduced-motion emulation, axe scan. Static review alone misses focus order, announcement, and jank. 4. **Rank, don't list.** Findings ordered by severity then by fix leverage (token-level fixes beat per-screen fixes).

Severity conventions

Accessibility findings rank by **WCAG level × user/task impact** — never by fix effort:

| Severity | Definition | |---|---| | **Blocker** | WCAG Level A failure preventing task completion for keyboard/AT users (trap, unlabeled required field, SR-silent error, invisible focus on core flow); data-loss UX (wiped form input, no-undo hard delete); broken Back button | | **Critical** | Level A/AA failure with workaround (contrast < 4.5:1 body text, dialog without focus return, missing landmarks); missing error/loading states on core flows; layout broken at 320px or 200% zoom | | **Major** | AA failure of limited scope; incomplete state coverage (no empty state, color-only validation); motion without reduced-motion handling; systemic token violations breaking theming; touch targets < 24px | | **Minor** | AAA/best-practice gaps (24–43px targets, terse alt text); visual drift (rogue radii/shadows/font sizes); generic-template aesthetics; missing polish states |

A small diff never downgrades severity; a locked-out user never rates "Minor".

Finding format

[SEVERITY] <domain>: <one-line problem>
  Where: <file:line or component/page>
  Rule: <rules/NN §section>