#BBDFBC · #C1D4FD
Four independent scores (read the one that fits your goal): Readability 0/100 (fail) · Harmony 69/100 (triadic (soft)) · Distinguishable 46/100 (somewhat similar) · Match 10/100 (different). There is no single “good/bad” — a pair can clash for text yet be great for an outfit.
Seafoam and Periwinkle are very different (ΔE 41). They have distinctly different hues (99° apart) and their lightness is similar, so they read as two same-weight colours.
Seafoam text on Periwinkle: 1.02:1 (Fail); Periwinkle text on Seafoam: 1.02:1 (Fail). Neither meets AA at body size — nudging one color to #446345 clears it.
Triadic (soft) — workable but not a textbook harmony (harmony 69/100). This is about how they look together (clothing, interiors, branding), independent of text contrast.
Not at body size — the best direction is only 1.0:1, below the 4.5:1 minimum. Nudging one colour to #446345 clears AA.
Their CIE76 ΔE is about 41 — very different.
clearly different colours (ΔE 41).
Explore each color: Seafoam #BBDFBC · Periwinkle #C1D4FD · Shades: Seafoam shades · Periwinkle shades · Contrast checker →