Playground demo: H-K salience colour solver.

Colours are (hue, chroma, tier) seeds; lightness is solved against a ground (background) lightness rather than hand-picked, compensating for the Helmholtz-Kohlrausch effect so every tier reads perceptually level regardless of terminal background. Cycling the ground resolves the same semantic seed to a different literal hex while the apparent-lightness relationship to the ground -- and thus how it reads to the eye -- stays constant.