#666ED2 · #8F7A00
Four independent scores (read the one that fits your goal): Readability 1/100 (fail) · Harmony 100/100 (complementary) · Distinguishable 100/100 (easy to tell apart) · Match 0/100 (different). There is no single “good/bad” — a pair can clash for text yet be great for an outfit.
Slate Blue and Olive are very different (ΔE 113). They have near-opposite hues (176° apart) and their lightness is different, giving a clear light/dark split.
Slate Blue text on Olive: 1.05:1 (Fail); Olive text on Slate Blue: 1.05:1 (Fail). Neither meets AA at body size — nudging one color to #0D0043 clears it.
Complementary — complementary — a recognised, balanced pairing (harmony 100/100). 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 #0D0043 clears AA.
Their CIE76 ΔE is about 113 — very different.
clearly different colours (ΔE 113).
Explore each color: Slate Blue #666ED2 · Olive #8F7A00 · Shades: Slate Blue shades · Olive shades · Contrast checker →