Review CSS color definitions and convert palettes to oklch(), a color format designed around human perception. Use consistent lightness steps to build color scales, dark-mode palettes, and interaction states, with guidance for wide-gamut displays.
Use when building a design token system, creating accessible colour palettes, generating colour ramps programmatically, or migrating a design system to support wide-gamut displays.
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See how to installThis skill organizes CSS colors using oklch() to create scales with consistent perceived lightness. It reviews color tokens, the shared settings that define a palette, and checks colors specified individually in hsl or hex. It explains L, C, and H—lightness, chroma, and hue—and converts colors so different hues use the same L value at each matching shade step.
Use it when maintaining a design system or organizing a palette whose colors appear uneven in brightness. It also helps establish common rules for dark-mode colors, hover colors, and active states. Support for displays that can show a wider color gamut is covered too.
oklch() with consistent lightness steps.”The skill covers @media (color-gamut: p3) as a way to apply wide-gamut colors on compatible displays. Check these display-dependent declarations alongside the regular palette definitions.
This overview was written by AI (OpenAI Codex) from the public SKILL.md. Check the original below for the exact behavior.
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Not counted in the score. Rated by AI (OpenAI Codex) as of Oct 23, 2026. Treat it as a guide and read the original before installing.
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HSL and hex colours are defined in the sRGB colour space, which is not perceptually uniform — a 10 % lightness change looks dramatically different depending on the hue. This makes creating accessible, harmonious palettes by hand extremely difficult. oklch corrects this: adjusting the L channel produces the same perceived brightness change regardless of hue or chroma, making it far easier to build accessible colour ramps, dark-mode palettes, and consistent hover/active states.
Check whether the CSS colour tokens use oklch() or a perceptually uniform colour space, or whether they use hsl/hex which may produce inconsistent perceived lightness across hues.
Convert the colour token palette from hsl/hex to oklch, ensuring the lightness (L) axis is consistent across all hues in the same shade step.
Explain what perceptual uniformity means in colour spaces, why oklch is better than hsl for design systems, and how the L, C, H channels map to human colour perception.
Review CSS custom properties for colour tokens. Flag palette definitions in hsl or hex that use hardcoded values without a systematic lightness ramp, especially if they are intended to be interchangeable shade steps.
For full implementation details, code examples, and framework-specific guidance,
see references/rule.md.
Rule page: https://frontendchecklist.io/rules/css/color-oklch
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