Color picker

A colour can be written several ways that all mean the same thing. Hex and RGB name the amounts of red, green and blue. HSL restates that as hue, saturation and lightness. OKLCH uses a perceptually uniform space, so equal changes in its lightness look equally different to the eye — which sRGB does not manage.

The contrast figures are WCAG 2.2 ratios, running from 1 for two identical colours to 21 for black on white. Normal body text needs 4.5, large text needs 3, and the stricter AAA level asks for 7. The catch is that the formula is a poor model of how contrast actually looks — it is generous to mid-greys and harsh on saturated blues — so treat a marginal pass as a reason to look at it, not as a verdict.