Imported from agents-inc/skills (src/skills/web-styling-design-tokens/SKILL.md). Install upstream with npx skills add agents-inc/skills --skill web-styling-design-tokens. Copyright stays with the author.

Design Token Patterns

Quick Guide: A design token system is a one-way dependency graph: primitives hold raw values, semantic tokens name intent, component tokens hold local exceptions. Consumers only ever touch the top two tiers. Deliver tokens as CSS custom properties -- primitives in :root, semantic aliases per scope, component tokens reading semantics. Name tokens for their role, never for the mode they happen to appear in (--color-surface-raised, never --color-dark-bg). Store complete color values, never bare channel triplets. When tokens must exist in more than one language, generate every output from one DTCG source rather than hand-maintaining parallel copies.

Detailed Resources:

examples/core.md - Tier construction, aliasing, naming grammar, CSS custom property delivery, @property registration
examples/scales.md - Generated spacing and type series, modular scales, fluid type, density multipliers
examples/pipeline.md - DTCG source files, Style Dictionary platforms, typed TypeScript export
examples/utility-framework-bridge.md - Feeding tokens into a utility-class framework without duplicating the source of truth
reference.md - Naming grammar table, DTCG $type reference, format names, authoring checklist

<critical_requirements>

CRITICAL: Before Using This Skill

All code must follow project conventions in CLAUDE.md (kebab-case, named exports, import ordering, import type, named constants)

(You MUST route every component style through a semantic or component token - NEVER let component CSS read a primitive token or a raw hex/px literal)

(You MUST name tokens for their role, NEVER for a mode or a literal value - --color-surface-raised, never --color-dark-bg or --color-gray-900-bg)

(You MUST store complete color values in tokens - NEVER bare channel triplets like 0 0% 100%, which break color-mix() opacity math and oklch() interpolation)

(You MUST keep the dependency flow one-way: primitive -> semantic -> component - NEVER let a primitive reference a semantic token, and NEVER create a cycle)

(You MUST generate every additional output from one source when tokens exist in more than one language - NEVER hand-maintain a TypeScript constant beside a CSS variable)

</critical_requirements>

Auto-detection: design tokens, design token, token tiers, primitive tokens, semantic tokens, component tokens, token aliasing, token naming, token taxonomy, DTCG, Design Tokens Community Group, $value, $type, Style Dictionary, style-dictionary, transformGroup, buildPath, css/variables, CSS custom properties, --color-, @property, token pipeline, spacing scale, type scale, modular scale, density tokens

When to use:

Standing up the token layer a design system will sit on
Deciding how many tiers a token set needs and what belongs in each
Naming tokens so they survive a rebrand, a new mode, or a density change
Delivering tokens as CSS custom properties with correct scoping
Building tokens from a DTCG source into CSS, TypeScript, or other platform outputs
Generating spacing and type series instead of hand-listing every step
Auditing an existing token set for tier leaks, mode-named tokens, or drift between languages

When NOT to use:

A project with a handful of colors and no theming ambitions -- a short :root block is the right amount of structure
A single-surface prototype that will not outlive the sprint
A codebase whose values are already fully derived from an upstream system you do not own

This skill does NOT cover:

Runtime theme application, mode switching, and FOUC prevention -- how a theme gets selected, persisted, and applied without a flash is a separate concern (web-styling-theming). This skill defines the token contract those mechanics switch between.
Utility-class authoring and usage -- writing markup with utility classes, variants, and responsive prefixes (web-styling-tailwind). This skill covers where tokens are declared; that skill covers how the generated classes are used.
Component variant APIs -- mapping props to class combinations (web-styling-cva). Variants consume component tokens; they do not define them.

Key patterns covered:

Token tiers: primitive -> semantic -> component, and when two tiers are enough
Naming grammar: category-property-variant-state, scale conventions, mode-free names
CSS custom properties as the delivery format, with scope-aware semantic aliases
@property registration where typed, animatable, non-inherited tokens earn it
Feeding tokens into a utility-class framework without forking the source of truth
DTCG-format source plus a build pipeline producing CSS and typed TypeScript
Scales as generated series, and density as a multiplier token

Philosophy

A token system is not a list of values. It is a one-way dependency graph with a naming contract, and its whole purpose is to put a layer of indirection between "what the value is" and "what the value means" so the two can change independently.

The three tiers exist to separate three kinds of change:

Tier	Answers	Changes when	Who reads it
Primitive	"What is this value?"	The palette or scale is regenerated	Semantic tokens only
Semantic	"What is this value for?"	The design language shifts, or a mode	Components, and component tokens
Component	"What does this part use?"	One component needs a local exception	That component only

Core principles:

One-way flow. Primitive -> semantic -> component. A primitive that references a semantic token has inverted the graph and made the palette un-regenerable.
Consumers touch semantics, never primitives. background: var(--color-surface-raised) survives a rebrand. background: var(--color-gray-100) does not.
Names encode role, not appearance, and never mode. The moment a token is called --color-dark-bg, it can only ever be correct in one mode, and every additional mode forks the name.
Every tier you add is indirection you pay for on every read. Three tiers is the ceiling, not the target. Component tokens are exceptions, not a mirror of the component tree.
The token set is the contract; the delivery format is an implementation detail. CSS custom properties, a typed TypeScript object, and a native platform file are three renderings of the same graph -- which is exactly why they must be generated, not typed twice.

Why a value that appears once still deserves a semantic token: the question is not "how many places use this?" but "when this changes, will everyone who uses it want to change together?" A token is a statement that a set of usages share a fate.

When two tiers suffice: a product with a single brand, a single mode, and no white-labelling can collapse component tokens away and let components read semantics directly. Add the component tier the first time a component needs a value that genuinely diverges from the semantic default -- not preemptively.

Core Patterns

Pattern 1: Token Tiers and the One-Way Graph

Primitives are the only tier holding literal values. Semantic tokens alias primitives and name intent. Component tokens alias semantics and exist only where a component diverges.

:root {
  /* Tier 1 - primitives: literal values, no meaning attached */
  --palette-slate-50: oklch(0.98 0.003 250);
  --palette-slate-900: oklch(0.21 0.02 250);

  /* Tier 2 - semantic: names intent, aliases a primitive */
  --color-surface-default: var(--palette-slate-50);
  --color-text-default: var(--palette-slate-900);

  /* Tier 3 - component: a local exception, aliases a semantic */
  --card-surface: var(--color-surface-default);
}

Key rules: a primitive never references anything, a semantic never holds a literal, a component token never reaches past the semantic tier. Circular references are a hard error in every conforming pipeline -- the graph must be acyclic.

Two tiers is a valid answer. Add the component tier at the first genuine divergence, not before. A component token that is a straight pass-through of a semantic token (--card-surface: var(--color-surface-default) with no override anywhere) is indirection that earns nothing -- delete it and let the component read the semantic directly.

See examples/core.md for a full three-tier set, the two-tier collapse, and the inverted-graph anti-pattern.

Pattern 2: Naming Grammar

A token name is a path read left to right, from most general to most specific. Fix the segment order once and every name in the system becomes predictable.

[namespace-]category-concept[-variant][-state][-scale]

--color-text-default            category=color  concept=text   variant=default
--color-text-danger-hover       + variant=danger + state=hover
--space-inline-sm               category=space  concept=inline scale=sm
--acme-color-surface-raised     namespace=acme (only when tokens ship outside the app)

Key rules: the category segment comes first so tokens sort into groups; state is always the last modifier so -hover and -pressed read consistently; a segment that is absent means "default" rather than being spelled out at every level.

Never bake the mode into the name. --color-dark-bg cannot be correct in light mode, so a second name has to exist, and now every consumer needs a conditional. The mode belongs in the scope that assigns the value, not in the identifier:

/* Bad - the name is only true in one mode */
--color-dark-bg: oklch(0.21 0.02 250);

/* Good - one name, value reassigned per scope */
--color-surface-default: var(--palette-slate-50);
[data-theme="dark"] {
  --color-surface-default: var(--palette-slate-900);
}

Scale conventions: numeric steps (50-950) for primitive ramps where the number is a position, t-shirt sizes (xs-xl) for semantic steps where the number would imply false precision. Do not mix the two conventions inside one namespace.

See examples/core.md for the full segment table, scale conventions, and the mode-in-name refactor.

Pattern 3: CSS Custom Properties as the Delivery Format

Custom properties are the delivery format because they are the only one that participates in the cascade -- reassigning a semantic token inside a scope re-themes every descendant with no rebuild and no re-render.

:root {
  --palette-blue-600: oklch(0.55 0.19 258);
  --color-action-default: var(
    --palette-blue-600
  ); /* semantic, global default */
}

/* A scope reassigns semantics; primitives never move */
[data-density="compact"] {
  --space-inline-md: var(--space-2);
}

.card {
  --card-padding: var(--space-inline-md); /* component token reads semantic */
  padding: var(--card-padding);
}

Key rules: primitives live in :root and are never reassigned; semantic tokens are the only tier a scope selector touches; component tokens are declared on the component's own selector so they inherit into its subtree and nowhere else. Never assign a fallback in the consumer (var(--color-x, #fff)) -- a missing token should be visible, not silently papered over.

Register a token with @property when it is animated, or when unintended inheritance would be a bug. Both syntax and inherits are required descriptors, and initial-value is required for any syntax other than *:

@property --card-elevation-alpha {
  syntax: "<percentage>";
  inherits: false;
  initial-value: 0%;
}

Registration buys typed interpolation (an unregistered custom property cannot be transitioned), plus a fallback to initial-value instead of an inherited garbage value when a computed value is invalid. It costs a declaration per token, so register selectively -- animated tokens and component-local tokens that must not leak, not the whole set.

See examples/core.md for scoping rules, inheritance traps, and @property registration in full.

Pattern 4: The Utility-Framework Bridge

When a utility-class framework consumes the token set, the CSS custom properties stay the single source of truth and the framework's theme block is a projection of them -- never a second place values are typed.

In Tailwind v4, @theme is a token-declaration surface: each variable in it generates utility classes and a standard CSS variable. @theme inline resolves the value directly into the generated utilities, which is what makes the mode-swappable bridge work:

@import "tailwindcss";

/* 1. Real tokens live here, mode-swappable, framework-agnostic */
:root {
  --app-canvas: oklch(0.98 0.003 250);
}
[data-theme="dark"] {
  --app-canvas: oklch(0.21 0.02 250);
}

/* 2. Projection - the framework consumes tokens, it does not define them */
@theme inline {
  --color-canvas: var(--app-canvas);
}

Key rules: @theme must be top-level -- it cannot be nested inside a selector or media query, which is precisely why the mode-swappable values live in :root/[data-theme] and only the alias goes in @theme. Without inline, the generated utility emits a variable reference that resolves at the wrong scope and the mode swap silently fails. Rule of thumb: put a token in @theme only when it should map to a utility class; everything else stays in :root.

Values must be complete colors. Opacity modifiers compile to color-mix(in oklab, var(--color-canvas) 50%, transparent), which requires a real color -- a bare channel triplet (0 0% 100%) produces invalid CSS and the utility silently drops.

See examples/utility-framework-bridge.md for the full bridge, namespace resets, and the duplicated-source-of-truth anti-pattern.

Pattern 5: DTCG Source and a Build Pipeline

A pipeline earns its keep the moment the same token must exist in a second language or a second platform. Source lives in DTCG format ($value / $type / $description, {alias} references), and every output -- CSS, typed TypeScript, native files -- is generated from it.

{
  "color": {
    "$type": "color",
    "palette": { "slate-50": { "$value": "#f8fafc" } },
    "surface": {
      "default": {
        "$value": "{color.palette.slate-50}",
        "$description": "Page background in the default mode"
      }
    }
  }
}

// style-dictionary config: one source, many platforms
export const config = {
  source: ["tokens/**/*.json"],
  platforms: {
    css: {
      transformGroup: "css",
      buildPath: "build/css/", // trailing slash is required
      files: [
        {
          destination: "tokens.css",
          format: "css/variables",
          options: { outputReferences: true }, // preserves var() aliasing
        },
      ],
    },
    ts: {
      transformGroup: "js",
      buildPath: "build/ts/",
      files: [{ destination: "tokens.ts", format: "javascript/es6" }],
    },
  },
};

Key rules: $type hoists to the closest ancestor group that declares it, so declare it once per group rather than on every token. The {group.token} alias always resolves to a whole $value -- property-level access needs JSON Pointer (#/color/blue/$value). DTCG ($value) and the original format (value) cannot be combined in a single instance -- pick one for the whole source tree. outputReferences: true is what keeps var() aliasing in the CSS output instead of flattening every semantic token to a literal.

When a pipeline does not earn its keep: one platform, one language, and hand-written CSS custom properties that nothing else consumes. A build step that produces exactly one file nobody else reads is cost with no payoff -- reach for it when a second consumer appears, not before.

See examples/pipeline.md for the full DTCG source tree, platform configs, typed TypeScript export, and the drift anti-pattern.

Pattern 6: Scales as Generated Series

Spacing and type are series, not sets. Express the generator -- a base and a ratio, or a base and a multiplier -- so every step is derivable and no step can be individually wrong.

:root {
  --space-base: 0.25rem;
  --space-1: calc(var(--space-base) * 1);
  --space-2: calc(var(--space-base) * 2);
  --space-4: calc(var(--space-base) * 4);
  --space-8: calc(var(--space-base) * 8);
}

Density is a multiplier on the semantic tier, not a second scale. One multiplier token re-scales the whole system without touching a single component:

:root {
  --density-scale: 1;
}
[data-density="compact"] {
  --density-scale: 0.75;
}

:root {
  --space-inline-md: calc(var(--space-4) * var(--density-scale));
}

Key rules: the multiplier applies where primitives become semantics, so component tokens inherit density for free. Type scales follow the same shape with a ratio instead of a multiplier, and fluid steps use clamp() with the min and max both derived from the scale rather than hand-picked. A calc() chain nested more than about three levels deep gets hard to debug -- if that happens, generate the resolved values in the pipeline instead.

See examples/scales.md for modular type scales, fluid clamp() steps, density multipliers, and generated-vs-hand-listed comparisons.

<decision_framework>

Decision Framework

How many tiers?

Does the product need more than one visual mode, brand, or tenant?
|-- NO --> Does any component need a value that diverges from the system default?
|   |-- NO  --> Two tiers: primitive + semantic
|   |-- YES --> Two tiers plus component tokens only for the divergent components
|-- YES --> Three tiers. Semantic tokens are the swap point; primitives never move.

Which tier does this value belong to?

Is it a literal (a hex, a rem, a ms)?
|-- YES --> Primitive. It gets a position-in-a-ramp name, not a meaning name.
|-- NO  --> Does more than one component share this decision?
    |-- YES --> Semantic. Name the role.
    |-- NO  --> Is the component genuinely diverging, or just the only current user?
        |-- Diverging   --> Component token
        |-- Only user   --> Semantic. One user today is still a shared decision tomorrow.

Does this need a build pipeline?

Do tokens need to exist in more than one language or platform?
|-- YES --> Pipeline. Generate every output; hand-maintaining two copies guarantees drift.
|-- NO  --> Are tokens consumed by anything outside this repository?
    |-- YES --> Pipeline. The published artifact needs a stable, versioned shape.
    |-- NO  --> Hand-written CSS custom properties. Add the pipeline at the second consumer.

Where does this token get declared?

Is it a primitive?
|-- YES --> :root, once, never reassigned
|-- NO  --> Does it change per mode, density, or tenant?
    |-- YES --> :root for the default, reassigned on the scope selector
    |-- NO  --> Is it local to one component?
        |-- YES --> On the component's own selector
        |-- NO  --> :root alongside the other semantics

</decision_framework>

Integration Notes

Consuming surfaces: the token set is a contract, and every consumer reads the same custom properties. A styling approach that can read var(--token) -- stylesheets, scoped component styles, inline styles, a utility framework's theme block -- needs no adapter. One that cannot read custom properties at runtime needs a generated artifact from the pipeline instead, which is exactly what a second platform target is for.

Publishing tokens: when tokens ship outside the repository that owns them, add the namespace segment to every name and version the generated artifact, not the source. Consumers pin the artifact; the source is free to reorganise as long as the generated names hold.

What the token layer does NOT own: how a mode is selected and applied at runtime, how utility classes are written, and how component props map to styles. Those consume tokens; they do not define them.

<red_flags>

RED FLAGS

High Priority Issues:

A component reading a primitive (background: var(--palette-slate-100)) -- the indirection layer is bypassed, so a rebrand has to touch every component instead of one semantic file. Alias a semantic token and use that.
Hex or px literals in component CSS -- an untracked token. It will not move with the system, will not respond to a mode change, and will not appear in any audit.
Mode baked into the token name (--color-dark-bg, --text-light-muted) -- the name is only true in one mode, so every additional mode forks the name and every consumer needs a conditional. Reassign one role-named token per scope instead.
Channel triplets as token values (--color-surface: 0 0% 100%) -- not a color, so color-mix(), oklch() interpolation, and every opacity modifier produce invalid CSS that silently drops the declaration. Store complete color values.
TypeScript constants and CSS variables maintained side by side -- they drift on the first change made in only one of them, and nothing fails loudly. Generate both from one source or keep only one.
An inverted or cyclic graph -- a primitive referencing a semantic token, or two tokens aliasing each other. Conforming pipelines error on cycles; hand-written CSS just resolves to nothing at runtime.

Medium Priority Issues:

Token-per-usage sprawl (--button-primary-hover-icon-margin-left) -- a token per property per element is a stylesheet with extra steps. Tokens encode shared decisions; a value used in exactly one declaration and shared with nothing is just a value.
A component tier that mirrors the component tree -- component tokens are exceptions, not coverage. A pass-through token that overrides nothing anywhere is indirection with no payoff.
Fallbacks in consumers (var(--color-surface, #fff)) -- hides a missing token behind a plausible value, so the bug ships. Let it be visibly broken.
Mixed scale conventions in one namespace (--space-sm beside --space-400) -- callers cannot predict which convention a given name uses, so every lookup is a guess.
Semantic names that describe appearance (--color-blue-action) -- half a semantic token. The role survives a rebrand; the colour name does not.
Skipping outputReferences in a generated CSS platform -- every semantic token flattens to a literal, so the aliasing that made the tier system worth building disappears from the output.

Common Mistakes:

Adding the component tier preemptively rather than at the first genuine divergence
Regenerating a primitive ramp and expecting semantics to follow, when semantics hold literals instead of aliases
Declaring $type on every token when it hoists from the closest ancestor group that declares it
Naming a state segment somewhere other than last, so -hover-danger and -danger-hover both exist
Treating density as a second spacing scale instead of a multiplier applied where primitives become semantics

Gotchas & Edge Cases:

@theme cannot be nested under a selector or media query -- it is top-level only. Mode-swappable values therefore live in :root / [data-theme], and only the alias goes in @theme inline. Omitting inline makes the generated utility resolve the reference at the wrong scope, and the mode swap fails silently rather than erroring.
@property requires both syntax and inherits; if either is missing the whole rule is invalid and ignored. initial-value is required for every syntax except *, and must be computationally independent -- 10px is valid, 3em is not.
An unregistered custom property cannot be transitioned or animated. It is treated as an untyped token and jumps between values. Registration is the only way to interpolate one.
CSS.registerProperty() takes precedence over @property for the same name, so a stray JS registration silently overrides the stylesheet.
DTCG {alias} syntax always resolves to a complete $value. Reaching into part of a composite token needs JSON Pointer (#/color/blue/$value). Referencing a group rather than a token is an error in current tooling.
DTCG ($value) and the original format (value) cannot be combined in one instance -- a half-migrated token tree fails in ways that look like missing tokens.
$type inheritance flows from the closest ancestor group that declares it, and a group must never contain both $value and child tokens -- that shape is neither a group nor a token.
Token names cannot start with $ or contain {, }, or . -- the period is reserved for alias path construction, so a name containing one produces an unresolvable reference.
Custom properties inherit by default, so a component token declared on a component selector leaks into every descendant including slotted children. inherits: false via @property is the fix when that matters.
calc() chains through several tiers resolve at use time, not at declaration time -- a unit error three aliases up surfaces as a silently dropped declaration at the consumer, with no indication of which link broke.

</red_flags>

<critical_reminders>

CRITICAL REMINDERS