tailwind-engineer

Apply utility-first discipline. Reach for design tokens before arbitrary values, compose with @apply only where it earns its keep, and reject inline style= drift. The skill is the how for any Tailwind-stack screen; pair with existing-ui-audit for the what already exists and fe-design for the why.

When to use

• Writing or reviewing Tailwind classes in Blade, Livewire, or React components.
• A diff introduces inline style= for dynamic values, hex codes not in tailwind.config, or !important.
• Class lists balloon past ~12 utilities and the component is hard to read or duplicate.
• German triggers: "stile mit Tailwind", "design tokens nutzen", "warum nicht inline?".

Do NOT use when:

• The stack is not Tailwind (vanilla CSS, CSS-in-JS, MUI) — skip.
• The question is component shape, not styling — route to ui-component-architect.
• An accessibility issue is the symptom (focus ring, contrast, hit area) — route to accessibility-auditor.

Procedure

1. Resolve to design tokens first

Inspect tailwind.config.{js,ts} (or the equivalent @theme block) and identify the configured tokens. Map every requested colour, radius, spacing, shadow, font-size to a configured token. If the design hands you #3B82F6, use bg-blue-500 (or the project's named token). Arbitrary values (bg-[#3B82F6], mt-[17px]) are a smell — accept only with a one-line comment naming the design source.

That paragraph is written for greenfield, and artifact-bound work inverts it. When a provided finished design is the spec (design-fidelity), #3B82F6 is a decision somebody already made and bg-blue-500 is a guess about it. Three obligations follow, and the third is the one this skill used to get wrong:

1. Do not snap. Replacing the artifact's value with the nearest configured token is the deviation the rule's Iron Law forbids — "NEVER SWAP … SPACING, OR COLOUR" without explicit confirmation. An artifact-derived exact value is not a smell here: it is the spec, and the source-naming comment the paragraph above asks for is what records it.
2. Translate once, not per call site. Where the artifact's literal genuinely needs to live in the project's system, add one named project token carrying that exact value and use it everywhere — one token the project owns beats N approximations of the same colour. That is a token duty, not a deviation: the value does not change.
3. Reconcile as a proposal, never autonomously. Report each value's distance to the nearest project token on the Reconciled: line below, and let the human decide. Writing a different project value because the difference looks small is exactly the unconfirmed swap (1) rules out — the mode table at design-fidelity.md:117-121 grants no visibility exemption, and structural grants only the filling of a spec that is genuinely silent, which an artifact stating #3B82F6 is not.

Why not "just approximate within tolerance", which is the eventual intent: that needs a tolerance to exist. There is none — no reconcile, tolerance, approximat or nearest in the rule or its guideline — and both the threshold and whether approximation is autonomous by default are owner decisions, tracked as blocker: approximation-tolerance and blocker: fidelity-default-flip on road-to-design-intent-conformance. Until they land, a skill granting that autonomy would be re-writing the rule from underneath it.

Structure, controls, grid and breakpoints are never this skill's to adjust; those stay 1:1 with the artifact and belong to the rule, not to a utility-class decision. Icons are out of scope here as well, and this skill asserts no obligation about them — the icon system belongs to icon-consistency. An earlier revision of this paragraph claimed icons "stay 1:1 with the artifact" with no citation of any kind, while putting them outside its own scope in the same sentence; the claim is withdrawn rather than defended, because a clause that reached the tree first does not thereby earn an evidentiary bar for its own reversal.

Token authoring (DTCG 3-layer model, CSS-var/Tailwind generation) lives in design-tokens; its tokens.ts validate --dir <path> is the single token-discipline linter — the mechanical check behind this rule (no hardcoded hex / px / rem outside the token files). That skill ships with the frontend-design pack: without it the rule above still binds and is checked by reading, not by a linter. Greenfield Tailwind config: bundled scripts/tailwind_config_gen.ts (Apache-2.0-derived, pure templating) scaffolds tailwind.config.{js,ts} per framework.

2. Compose, don't inline

Inline style="..." is allowed only for runtime-computed values the build cannot know (server-pushed colour, animated transform target). Static values inline are a regression — replace with a utility, an arbitrary value, or a token extension.

3. Order classes for scan-ability

Group by axis: layout → box-model → typography → colour → state → responsive. Most projects pin this with prettier-plugin-tailwindcss; if the plugin is configured, run it; if not, follow the order manually. Reviewer should read intent in one pass.

4. Extract only when duplicated ≥ 3 times

The first two repetitions of a utility-class string are noise; the third is a pattern (the utility-class row of the per-class canon, abstraction-thresholds). Extract via:

Mechanism	When
Component (Blade/Livewire/React)	Different content, same shell
Class string constant	Same shell, different consumers in same file
@apply in CSS	Cross-file shared visual primitive (button, badge)
Tailwind plugin	Tokens or variants, not classes

@apply for a one-off is a regression — keep utilities inline until the third use earns extraction.

5. Responsive + dark + state in that order

Class order within an axis: base → sm: → md: → lg: → xl: → dark: → state (hover:, focus:, disabled:, aria-*:). Mixing the order makes diffs noisy. State on top of dark on top of responsive matches Tailwind's cascade and reads top-down.

Output format

When reviewing or proposing styles, return:

1. Token map — every colour, spacing, radius, shadow, font-size mapped to its configured token; arbitrary values flagged with the design source they cite. Artifact-bound work adds a Reconciled block here: one line per value, as <artifact value> → <kept, or the token that carries it exactly> (<distance to the nearest project token>). This is the destination "report the distance" means; without it the obligation has nowhere to land and is unobservable in the deliverable.
2. Class list — ordered (layout → box-model → typography → colour → state → responsive); inline-style use justified per element.
3. Extraction + risk call-out — component / constant / @apply / none with reason; risks named (arbitrary values, !important, dark-mode gaps, non-token references).

Concrete shape:

Element:        <selector or component name>
Token map:      <colour/spacing/etc → config token>
Reconciled:     <artifact value → kept or exact-carrying token, + distance>
Class list:     <ordered classes>
Inline style:   <only if runtime-computed; else "none">
Extraction:     <component | constant | @apply | none — reason>
Risks:          <arbitrary values, !important, dark-mode gaps>

Gotcha

• space-x-* / space-y-* collide with flex-wrap and RTL — use gap-* on the flex/grid parent unless the design demands otherwise.
• dark: variants need a token map in both modes; one-sided dark styling is half a feature.
• Arbitrary values (mt-[17px]) survive Tailwind upgrades but break the design system; they accumulate silently. Artifact-bound is the exception, not a loophole: a value the provided design specifies is not accumulation, and step 1's three obligations decide it. An arbitrary value nobody can trace to a source is still the smell this bullet is about.
• The carrier is CSS or a utility class; the value is the design's. Static presentation belongs in CSS / tokens / classes — style= is for what only the runtime knows (a computed width, a live transform, a measured offset). Porting an artifact's inline style= into classes is therefore expected and is not a deviation, as long as the resolved value comes out identical. Changing the carrier is free; changing the number is not.
• @apply inside component CSS interacts with PurgeCSS — keep it in files Tailwind scans, not in vendor CSS.
• Anti-AI-slop catalog. The bullets below are the Tailwind-specific manifestations of the stack-agnostic patterns in docs/guidelines/design-antipatterns.md (C1 gradients, T7 fonts, L1/L2 layout, V1 side-stripe). Pull the catalog for the full list; the objective subset (contrast, font-size floor, reduced-motion) is validated via accessibility-auditor's checklist — cite its verdict rather than eyeballing.
• Anti-AI-slop: gradients. Unless audit-pinned or brief-explicit, avoid the default purple-to-blue / cyan-to-pink gradients on white — they read as auto-generated (catalog C1/C2). Reach for a single accent from the token map, or a duotone built from configured tokens.
• Anti-AI-slop: typography. Unless audit-pinned, avoid surfacing the default as the visible body face — Inter as a template webfont, or font-sans (Arial / Helvetica). If tailwind.config pins a font family, use it; if not, treat the missing token as a gap to flag, not a license to ship the OS default.
• Anti-AI-slop: layout. Unless audit-pinned, the centered hero + 3-column features + CTA stack is the AI-template tell. Break the grid intentionally (asymmetric column split, overlap, diagonal flow) when the brief allows; cite the design brief's aesthetic: line if fe-design's aesthetic-direction section produced one.

Taste Dials

When DESIGN.md declares ## Taste Dials, honour them: Variance → layout-family spread + asymmetry tolerance; Motion → animation budget + reduced-motion posture; Density → spacing scale + information-per-viewport. Absent → follow the design brief's inferred dials.

Security constraints

scripts/tailwind_config_gen.ts is the only shipped script, started as:

node <skills-root>/tailwind-engineer/scripts/tailwind_config_gen.mjs \
  [--framework react|vue|svelte|nextjs] [--output PATH] [--validate-only]

• What it may touch — exactly one file: --output PATH, or tailwind.config.ts / .js in the current working directory when no --output is given. It reads nothing from the project.
• What it must never do — write anywhere other than that one path, reach the network, or spawn a subprocess. It does none of these.
• Default invocation — mutating, and stated here because it is a real exception rather than a comfortable one: a bare invocation writes tailwind.config.ts into cwd, overwriting an existing config without prompting. --validate-only is the read-only path — it prints the generated config to stdout and writes nothing. Run --validate-only first, and pass --output when the target is not the cwd default. This default contradicts skill-writing's "never mutate on a bare invocation" line; it is recorded rather than silently tolerated, and changing the script's default is a caller-visible behaviour change that belongs in its own change, not here.
• Outbound — nothing. No network access.

Do NOT

• Do NOT run tailwind_config_gen bare in a project that already has a tailwind.config.* — it overwrites without asking. Use --validate-only first, then --output at the intended path.
• Do NOT add !important to win a specificity fight; restructure the cascade or extract the conflicting style.
• Do NOT introduce a new colour outside tailwind.config without also adding the token; one-off hex codes drift the system.
• Do NOT use @apply to avoid utility verbosity inside a single component — extract the component instead.
• Do NOT ship style= for static values; that is a CSS regression the linter will not catch.