Two colors in, a WCAG verdict out — with real text to judge by eye and, when it fails, the nearest shade of your color that passes. Not a random passing color: yours, adjusted the minimum amount.
The ratio compares relative luminance — roughly, how bright each color looks to a human eye — between text and background. WCAG AA (the common legal and contractual bar) wants 4.5:1 for body text and 3:1 for large text (24px+, or 18.7px bold). AAA raises those to 7:1 and 4.5:1. The classic trap: mid-gray text on white reads fine on your bright monitor at midnight and disappears on a dim laptop in a sunlit café — the ratio predicts the café.
The fix suggestion keeps your hue and saturation and moves only lightness until the pair passes AA — so your brand blue stays your brand blue, just enough darker or lighter to be read. Found the color on a real surface? Grab it with the detector first, then check it here.