Precisely this—while we only mention CIELAB in the post, we also tested other perceptually uniform color spaces in addition to Lab (and can switch between them in the color tool). In particular, we also tested CIECAM02 extensively. We found that both were sufficient for the level of precision we needed and that Lab’s simpler lightness calculations are more closely aligned with how WCAG contrast ratios are calculated. We’re definitely open to testing other color spaces in the future as we continue to refine our color palettes.