Colors
This skill builds and audits color systems. It generates ramps, maps their steps to roles and token names, converts notation and measures rendered contrast pairs.
Never report a contrast value you did not measure, and never estimate a color you could compute. Notation, a tinted neutral and a gradient's interpolation space are project choices, not findings. A broken role mapping, a failing pair and an out-of-gamut step are findings. Perceived lightness throughout means OKLCH L, from 0 to 1.
Whether a pair is required to pass belongs to better-accessibility. Surfaces, shadows and icon color belong to better-ui.
Match the project's color system
Reuse the project's tokens and notation. A consistent hex system beats hex with oklch() scattered through it.
For a new system, oklch() is the best default, because its numbers behave the way the ramp rules below describe. Everywhere else, a color library produces the same ramp in the project's own notation (color-formats.md).
A system is ramps, not colors
One neutral ramp, one accent ramp and only the status ramps the product actually renders. A warning ramp nothing imports is maintenance for zero pixels. A second accent hue earns its place only when two things must be distinguishable at a glance. Otherwise use more steps of the one accent ramp.
Every step has a job
A ramp is not a gradient to pick from by eye. Each step exists because a role needs it: page background, component hover, border, solid fill, body text. Do not generate a step no role consumes. Both the Tailwind 50–950 and Radix 1–12 conventions map to those roles (palette-structure.md).
Name primitives by hue, semantics by role
Primitives name a value (--blue-600) and are never applied in a component. Semantic tokens name a job (--color-text-secondary), point at a primitive and are the only tier components reference. That seam is what lets a theme repoint colors without touching components (token-naming.md).
Use a token only in its role
Never borrow a token because its value is right today. A separator used as a text color works until borders get lighter, and then the text goes with them. If a role has no token, add the token.
Hold the hue across the ramp
A ramp holds one hue end to end, peaks in vividness mid-ramp and steps more finely at the light end. Build it with a color library, never by eye (palette-generation.md).
One color, one meaning
Use a color for one purpose across the whole interface, treating anything within 15° of OKLCH hue as the same color (color-usage.md). Never let color be the only carrier of meaning. Pair it with an icon or a label, a requirement better-accessibility owns.
Fill exactly one action per view
When filled color encodes primary emphasis, one primary action gets it and peers stay neutral. Put the color on the background, not the label. A filled button reads as primary across the room; accent-colored text on a neutral button reads as a link.
Keep an established hierarchy that already signals emphasis another way. Several colored backgrounds are fine when they encode distinct states or categories rather than competing as peers.
Measure the rendered pair, then report
Measure a foreground against the background it actually renders on, not the page background. When a pair fails, report the pair, its measured value and the threshold it misses, then leave the colors alone. They are a design decision. Change them only when asked, and remeasure after (contrast.md).
Pick a gradient's interpolation space
The space is a look, not a correctness setting. Default to in oklab, and reach for in oklch when a two-hue gradient goes gray in the middle (color-usage.md).
Before you finish
| Pattern | Fix |
|---|---|
A hex, rgb( or oklch( literal in a component file where a token exists | Reuse or add the role token, in the project's notation |
One oklch( value in a codebase otherwise written in hex | Write it in the established notation unless a migration is in scope |
var(--blue-600) or bg-blue-600 in a component file | Point a semantic token at the primitive and use that |
A semantic name containing a hue or a component, as in --color-blue-button or --color-sidebar-gray | Rename it for its role: --color-accent-solid, --color-bg-surface |
--color-primary and --color-text-primary both defined | Rename the brand token accent |
A border or separator token inside color:, or a text token inside background: | Add a token for the missing role |
hsl( ramp values that differ only in lightness | Rebuild in OKLCH with a constant hue |
50–200 stepping as far apart in OKLCH L as mid-ramp steps do | Tighten the light end to about 0.04–0.05 per step |
| One chroma or saturation number copied across every hue's ramp | Use the same proportion of each hue's own maximum |
A status hue within 15° of the accent hue | Move it at least 15° away, or give the destructive action a distinct treatment |
| Dark tokens equal to the light ramp in reverse step order | Lower the accent's chroma, widen the dark end and remeasure every pair |
Color tokens set under both prefers-color-scheme and a .dark class | Pick one switching mechanism and use it throughout |
| A contrast fix that changes hue and leaves lightness | Change lightness, the channel contrast responds to |
prefers-contrast: more overriding a color for both appearances in one block | Give each appearance its own increased-contrast value |
Text on a color with alpha, such as /50, rgba( or color-mix( with transparent | Measure the rendered result, or use a solid token |
text-white on a Tailwind 500 fill | Measure it; white on most 500 hues fails 4.5:1, so move the fill to 600 |
oklch() chroma beyond sRGB with no sRGB value declared before it | Declare the sRGB value first, then the vivid one inside @media (color-gamut: p3) |
Reporting
Severity. HIGH makes content unreadable or assigns a misleading semantic color. MEDIUM is a noticeable theme, token or gamut failure. LOW is isolated polish.
Three symptoms are HIGH on sight whatever the surface, matching better-interface's escalation triggers. They are body or control text whose rendered pair fails its required ratio, state or meaning carried by color alone and a semantic color used against its meaning.
Verification. Without a browser: token values, the gamut of every declared color, both theme blocks present and contrast computed from the declared token pair. With one: the background actually rendered behind the text, including opacity and any image beneath it, measured in both light and dark. Report every check you could not run as Not verified.
Format. Group findings under the principle each violates, ordered by severity, one row per root cause listing every location it appears in:
| Severity | Location | Before | After | Why |
|---|
Location is path/to/file:line. Why names the principle and the user impact.
End with Block when any HIGH remains, Approve otherwise, leaving the rest in the table as work to do. Never Approve coverage you did not inspect. With nothing to report, state "No actionable color findings" and report verification.