Fade text with a slider until it only just passes WCAG AA, then see how close you landed.
Fade the text until it only just passes AA contrast for body text, 4.5:1. Closer to the line scores more; below it
scores nothing.
Designers often chase the lightest grey that still passes. Landing right on the line leaves no room for screens,
glare or anti-aliasing, so a little headroom is kinder in real use.