The six core harmonic relationships
Complementary: 180° apart. Maximum hue contrast. Effective for accent/call-to-action pairings, sport branding, and high-energy identities. Risk: chromatic vibration at full saturation. Fix: desaturate the dominant color. Analogous: 30-60° arc. Minimal hue contrast. Natural, cohesive, and suitable for extended-use UI. Risk: monotony. Fix: add significant lightness variation. Triadic: 120° apart, three colors. Balanced contrast with variety. Common in playful or educational brands. Risk: visual noise. Fix: make one color dominant, one secondary, one accent. Split-complementary: one base + two colors 150° away (flanking the complement). Variation on complementary with reduced tension. Useful when full complementary feels too aggressive. Tetradic/double-complementary: two complementary pairs. Maximum palette variety. Difficult to balance without one pair overwhelming the other. Best used with one pair as primary and one as secondary. Square: four colors at 90° intervals. Even spacing across the wheel. Produces rich, complex palettes. Rarely used in UI; more common in illustration and print.
