Apply Design System

Use the design system that exists in the target app now, not the oldest generic theming examples in the repo.

Source Of Truth Order

When sources disagree, use this order:

1. Existing component API contracts in the code you are editing
2. App-level token registration in the target app's globals.css / Tailwind v4 @theme
3. Theme package tokens in packages/themes/<theme>/src/tokens.ts
4. Shared Tailwind preset/plugin wiring
5. Older handbook examples and generic docs

For example, reception exposes utilities through apps/reception/src/app/globals.css using @theme { --color-surface-2: var(--surface-2) ... }, so classes like bg-surface-2, text-muted-foreground, and border-border-strong are valid even when they are not literal keys in tokens.ts.

Profile-Aware Defaults

Before applying any default styling, read the design profile for the target theme at packages/themes/<theme>/src/design-profile.ts. Profile values are authoritative over the generic examples in this skill.

Conditional Rules

• If defaultElevation: "flat" — do not add shadow classes (shadow-sm, shadow-md, shadow-lg) unless a page-level design spec explicitly overrides. Flat means flat.
• If defaultElevation: "subtle" — use shadow-sm only. Do not escalate to shadow-md or shadow-lg without a design spec override.
• If defaultBorder: "none" — do not add border or border-border classes to cards or surfaces. The brand intentionally uses borderless containers.
• If defaultBorder: "subtle" — use border-border-muted, not border-border-strong.
• If defaultRadius: "sm" — use rounded-sm, not rounded-lg. The brand uses small corners.
• If defaultRadius: "none" — use rounded-none. The brand uses sharp edges.
• If defaultRadius: "xl" — use rounded-xl. The brand uses large, soft corners.
• If colorStrategy: "monochromatic" — do not use accent token (bg-accent, text-accent-fg). Stick to primary + neutrals only.
• If colorStrategy: "restrained" — use accent sparingly (CTAs and 1-2 highlights per page maximum).

General rule: Read the design profile before applying any default. The profile is more specific than the examples below and takes precedence when they conflict.

Theme Asset Awareness

Before recommending specific token classes, check packages/themes/<theme>/src/assets.ts for available theme assets:

• Fonts: If assets.fonts.heading is defined, use that font family for headings instead of defaulting to font-sans. If no heading font is defined, font-heading or font-sans remains correct.
• Gradients: If assets.gradients defines named gradients (e.g., hero, header), these are available via CSS custom properties. Reference them rather than composing ad-hoc gradient values.
• Shadows: If assets.shadows defines brand-colored shadows (e.g., brandPrimary10), prefer them over generic shadow-sm/shadow-md for branded surfaces.
• Keyframes: If assets.keyframes defines animations (e.g., fade-up, slide-down), use them for motion instead of inventing new keyframes.
• Brand colors: If assets.brandColors defines named colors beyond the semantic palette, they are available as CSS custom properties for brand-specific use cases.

If assets.ts does not exist or exports empty collections, the brand has no custom assets. Use base tokens as documented below.

Core Rules

• Prefer public DS component props over class-level restyling when the component already exposes the contract.
• Prefer semantic utility classes over raw color values.
• Prefer app/theme token aliases over ad hoc component-local CSS variables.
• Do not edit generated token artifacts directly.
• Do not assume every hsl(var(--...)) pattern is valid in JSX utility classes; check whether the app already exposes a semantic alias first.

Component Contracts First

Before adding classes, check whether the primitive already exposes the right contract.

Common current contracts:

• Button, Tag, Chip, similar action/status primitives:
  • color="primary|accent|success|info|warning|danger"
  • tone="solid|soft|outline|ghost|quiet"
  • size="sm|md|lg"
• Core primitives and surfaces may expose:
  • shape="square|soft|pill"
  • radius="none|xs|sm|md|lg|xl|2xl|3xl|4xl|full"

Use those props before hardcoding rounded-*, bg-*, or size classes in reusable components.

Token Plumbing Model

This repo currently has two valid token-consumption paths:

1. Shared preset/plugin utilities

Many apps rely on shared semantic utilities such as:

• Backgrounds: bg-bg, bg-primary, bg-accent, bg-muted, bg-panel, bg-surface
• Text: text-fg, text-primary-fg, text-muted-foreground
• Borders: border-border, border-input, ring-ring

These are commonly wired through shared Tailwind config/plugin layers that still use hsl(var(--...)) under the hood.

2. App-level Tailwind v4 @theme aliases

Some apps, including reception, register additional semantic aliases in app globals.css.

Examples of valid app-level utilities:

• bg-surface-2
• bg-surface-3
• text-foreground
• text-muted-foreground
• border-border
• border-border-strong
• bg-input

When working in an app with @theme, treat those aliases as first-class utilities.

Color Guidance

Prefer these kinds of semantic utilities:

• Backgrounds:
  • bg-bg
  • bg-panel
  • bg-surface
  • bg-surface-2
  • bg-surface-3
  • bg-primary
  • bg-primary-soft
  • bg-accent
  • bg-muted
• Text:
  • text-fg
  • text-foreground
  • text-muted-foreground
  • text-primary-fg
  • text-primary-foreground when that alias already exists in the target app
• Borders/rings:
  • border-border
  • border-border-strong
  • border-border-muted
  • ring-ring

Use opacity modifiers when they are part of a semantic class, for example:

• bg-primary/90
• bg-surface-2/60
• text-foreground/80

Those are not the same thing as hardcoded colors.

Spacing, Radius, Shadow, Typography

Prefer the repo scales:

• Spacing: 0, 1, 2, 3, 4, 5, 6, 8, 10, 12, 16
• Radius: rounded-none|xs|sm|md|lg|xl|2xl|3xl|4xl|full
• Shadow: shadow-sm|md|lg
• Typography:
  • sizes: text-xs|sm|base|lg|xl|2xl|3xl|4xl
  • weights: font-normal|medium|semibold|bold
  • families: font-sans|heading|mono

If a primitive already exposes size, shape, or radius, use the prop instead of duplicating the class at call sites.

Common Patterns

Prefer patterns like:

<div className="rounded-lg border border-border bg-surface text-foreground shadow-sm p-6" />

<div className="rounded-lg border border-border-strong bg-surface-2 text-foreground shadow-lg" />

<Button color="primary" tone="solid" size="lg">Save</Button>

<Input className="bg-input text-foreground" />

Bracket Syntax: Allowed Vs Not Allowed

Do not treat all bracket syntax as invalid.

Usually acceptable:

• data-[state=open]:...
• aria-[selected=true]:...
• valid layout values with no DS utility equivalent, such as viewport-safe units
• targeted selectors needed to style DS primitives when no prop/API exists

Usually not acceptable:

• bg-[#ff0000]
• text-[rgb(255,0,0)]
• border-[oklch(...)] in component JSX when a semantic token should exist
• arbitrary spacing/sizing when the repo scale already covers it

When Tokens Do Not Exist

Use the narrowest correct layer.

1. Reuse an existing semantic utility if one already expresses the intent.
2. If the app needs a new alias for an existing theme token, add it in the target app's globals.css @theme block.
3. If the theme truly needs a new semantic token value, add it in packages/themes/<theme>/src/tokens.ts.
4. Regenerate any derived artifacts when the theme pipeline requires it.
5. Only update shared token/preset layers when the token is genuinely cross-app design-system surface area.

Do not jump straight to packages/design-tokens/ or Tailwind config for app-local needs.

Anti-Patterns

• Hardcoded hex/RGB/HSL/OKLCH colors in component JSX
• Default Tailwind palette classes such as bg-red-500
• Editing generated tokens.css directly
• Replacing DS component props with local class hacks in reusable primitives
• Assuming handbook examples are authoritative when the target app's globals.css and current components say otherwise

Quick Checks Before Editing

• Which app am I in?
• Does this app expose extra semantic aliases in globals.css?
• Does the component already expose color, tone, size, shape, or radius?
• Is this a theme-token change, an app-alias change, or just a component usage change?
• Am I about to introduce a raw value where a semantic token already exists?

Integration

This skill is a supporting reference, not a pipeline stage.

• Role: Current-state design-system guidance for token usage, DS component contracts, and app-level alias handling.
• Consumers: lp-design-spec, tools-ui-frontend-design, lp-design-qa, tools-refactor, and UI implementation/review work generally.
• Not a pipeline stage: consult it when UI work touches tokens, classes, component props, or design-system contract decisions.