Harmony rules: complementary, triad, tetrad, and 9 more

The harmony rule (top toolbar, "Auto" by default) constrains the generator to colors that follow a specific relationship on the color wheel.

Options:

• Auto — no constraint, fully random.
• Analogous — colors next to each other on the wheel.
• Complementary — opposite ends of the wheel.
• Split complementary — base color + two adjacent to its complement.
• Triad / Tetrad / Square — equally spaced.
• Monochromatic — same hue, different lightness/saturation.
• Shades / Tints — variations of a single anchor.

Lock at least one swatch first, then change the rule — the rest of the palette will regenerate around your locked colors.