fracazofracazo/design-system/skills/colors/SKILL.md

colors

Skill4 starsChanged 53 days agoMITView on GitHub

OKLCH color space and color usage for web projects. Convert hex/rgb/hsl to oklch, generate palettes, check contrast, handle gamut boundaries, theme with Tailwind v4, and apply color with meaning. Triggers on oklch, color conversion, palette generation, contrast ratio, gamut, display p3, design tokens, semantic color tokens, hue drift, chroma, dark mode colors, accent color, color meaning, light and dark appearance, increased contrast.

1 other project uses a version of this.

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ivancidev/ivancidev-blogtheir own version, first seen Apr 19, 2026

Other versions1 project uses a version of this.
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ivancidev/ivancidev-blog★ 0same name
How matches are found. Word for word: the exact same text. Edited: shares passages with this file (“99% same” means 99% of its five-word phrases also appear here; 10% or more counts). Their own version: similar meaning, or, weakest, the same name. We can’t tell which project had it first. Projects are counted among the 200 most-starred candidates, and mentions are links to the repository we found, up to 50 per site, so both counts are a floor.
In this repository9 other files it gives its agents.
- CLAUDE.mdCLAUDE.md
- template/CLAUDE.mdCLAUDE.md
- accessibilitySkill
- interfaceSkill
- layoutSkill
- product-designSkill
- typographySkill
- uiSkill
- writingSkill

The file

We split this skill into the rules it gives an agent

4 rules. About 0 are common, 2 are distinctive, and 2 are very specific to this project.

≈0
Common · estimate
Many files like this have a rule of this kind.
≈2
Distinctive · estimate
This author's own choices. Worth a look.
2
Very specific
Tied to their project's names, files or tools. Probably skip.

Common
Distinctive
Very specific

Distinctive:
Respect the existing system: Do not convert notation merely because this skill was loaded.
line 30
Distinctive:
Finite gamut: Not every oklch value maps to a displayable sRGB color.
line 34
Very specific:
Use this format only when the user asks for a standalone color review.
line 91
Very specific:
When there are no findings, omit the table, state "No actionable color findings", report verification, and end with Approve.
line 119

≈ “Common” is an estimate: at least 1 in 5 of the 350,495 skill files we read have a rule of the same kind, not the same words. “Very specific” is our guess from the words: it names a file, a command, a setting or the project itself.

Keep what fits and drop the rest. Your version, ready for your agents.

Files

SKILL.md

OKLCH Colors

OKLCH is a perceptually uniform color space where lightness, chroma, and hue are useful design controls. Use it when the project already uses OKLCH, when creating a new color system, or when the user asks for conversion or palette work. Otherwise preserve the project's established tokens and notation: a consistent hex or RGB token system is better than introducing a second color representation for an isolated fix. To explore interactively, visit oklch.fyi.

This skill does not own focus, keyboard, ARIA or live regions (accessibility), grouping, logical properties or RTL (layout), voice, labels or empty states (writing), faces, measure or tabular numerals (typography), or radius, shadow and motion (ui).

Status ink pair

On this system, a status wash is not a text colour. --status-want-ink is the label on --status-want-soft, and --status-no-ink is the label on --status-no-soft. Measure the rendered pair. Both must clear APCA |Lc| 60 (non-body text) and WCAG 4.5:1 for normal text, in light and dark. The fill (--status-want, --status-no) stays a dot or a background. --status-ifnec has no separate ink: its text uses the brand ink or --highlight-ink. Do not put the fill color in the text.

Quick Reference

Category	When to use	Reference
Conversion	Hex/rgb/hsl to oklch	color-conversion.md
Palettes	Generate scales, multi-hue, dark mode	palette-generation.md
Contrast	APCA/WCAG checks, reporting failures, fixing on request	accessibility-contrast.md
Gamut & Tailwind	P3 fallbacks, `@theme` scales, gamut clamping	gamut-and-tailwind.md
Usage	Semantic tokens, one meaning per color, primary-action emphasis, appearance variants	color-usage.md

Core Principles

1. Use a Perceptual Color Space

Respect the existing system. Do not convert notation merely because this skill was loaded. Reuse the project's semantic tokens and authoring format unless the task includes a color-system migration.
Perceptual uniformity. Equal L steps = equal brightness. oklch(0.5 ...) is visually mid. HSL's lightness: 50% varies wildly by hue.
Stable hue. HSL blue shifts toward purple as lightness changes. OKLCH hue stays constant across the full lightness range.
Independent chroma. Chroma is an absolute measure of colorfulness that doesn't depend on lightness. HSL saturation does.
Finite gamut. Not every oklch value maps to a displayable sRGB color. High-chroma values at certain hues will clip; gamut awareness is required.

2. Write and Format OKLCH Consistently

oklch(L C H)
oklch(L C H / alpha)

Channel	Range	Description
L (Lightness)	0–1	0 = black, 1 = white. Perceptually uniform.
C (Chroma)	0–~0.4	Colorfulness. 0 = gray. Max depends on L and H.
H (Hue)	0–360	Hue angle in degrees.
alpha	0–1	Optional transparency. Slash syntax.

oklch(0.637 0.237 25.331)
oklch(0.8 0.05 200 / 0.5)

Use three decimal places for L and C and up to three for H. Drop trailing zeros and format -0 as 0. OKLCH is Baseline 2023; when support requirements are unusually broad, check the target project's browser matrix instead of relying on a fixed global-coverage percentage.

3. Measure Contrast, Gamut, and Palette Behavior

Rule	Value
Light/dark boundary	L > 0.73 = light background → dark text; below it, light text still scores higher
Lightness gap (light bg)	Foreground L < 0.35 when background L > 0.9
Lightness gap (dark bg)	Foreground L > 0.9 when background L < 0.25
Hue drift threshold	> 10° spread across palette steps = visible drift
APCA body text	\|Lc\| >= 75 minimum, >= 90 preferred
APCA non-body text	\|Lc\| >= 60 minimum
WCAG 2 normal text	4.5:1 AA, 7:1 AAA
Contrast fix (only when asked)	Adjust L first; preserve C and H when possible, then remeasure the rendered pair

Common Mistakes

Issue	Fix
Raw color bypasses the project's semantic token system	Reuse or add the correct role token in the project's existing notation
Isolated OKLCH value introduced into a hex/RGB codebase	Preserve the established notation unless the task includes a color-system migration
HSL palette ramp with hue drift	Rebuild with constant oklch hue
Failing contrast (check foreground vs its background using APCA)	Report the pair, its measured Lc and the threshold it misses; change colors only when asked (then adjust L, keep C and H)
High chroma without gamut check	Clamp to max chroma for the L/H in sRGB
Same absolute C across different hues	Use same C% (percentage of max) for consistent vividness
P3 color without sRGB fallback	Add `@media (color-gamut: p3)` pattern
Dark mode created by mechanically reversing the light palette	Use the light palette as a starting point, then tune chroma and lightness and recheck every foreground/background pair
Hex in Tailwind v4 `@theme`	Convert to oklch values
Alpha with comma syntax	Use slash: `oklch(L C H / alpha)`
Same hue means two different things (link color reused decoratively)	One color, one meaning; give the second use a neutral
Semantic token used outside its role (separator as text)	Add a token for the missing role; never borrow by value
Several colored control backgrounds in one view	Fill only the single primary action; secondaries stay neutral
Palette verified only in light mode	Recheck every foreground/background pair in both appearances

Review Output Format

Use this format only when the user asks for a standalone color review. When interface orchestrates the review, provide domain evidence and findings to that skill and let its output format, severity scale, consolidation rules, cap, and verdict take precedence.

Present the standalone review in two parts.

Findings

Group all confirmed findings by principle. Use a markdown table with Severity, Location, Before, After, and Why columns. Never use separate "Before:" / "After:" lines.

Severity: HIGH makes content unreadable or assigns a misleading semantic color; MEDIUM creates a noticeable theme, gamut, or consistency failure; LOW is isolated polish.
Location: cite path/to/file:line. If the artifact has no source files, cite the exact screen and component instead.
Before / After: show the current value or token and the exact replacement.
Why: name the violated principle and include measured contrast or gamut evidence when relevant.

Consolidate a repeated systemic issue into one row and list every affected location. Omit principles with no findings.

Severity	Location	Before	After	Why
MEDIUM	`src/theme.css:18`	`color: #3b82f6`	`color: oklch(0.623 0.188 259.815)`	New project colors use OKLCH tokens
MEDIUM	`src/palette.ts:31`	Same absolute C across hues	Same C% of each hue's maximum chroma	Equal chroma values do not appear equally vivid across hues
HIGH	`src/theme.css:52`	P3 color with no fallback	Add an sRGB fallback before `@media (color-gamut: p3)`	The color fails on non-P3 displays

Verification and Verdict

After the findings:

Verification: list the exact checks run and their observed results, including contrast measurements, gamut checks, and both light and dark appearances when applicable. If a check was not run, state what still needs verification.
Verdict: Block if any HIGH finding remains, Needs changes if only MEDIUM or LOW findings remain, and Approve only when no actionable findings remain.

When there are no findings, omit the table, state "No actionable color findings", report verification, and end with Approve.

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