#66EEBBOnsen (#66EEBB) is a very light, saturated blue-green with an OKLCH hue of 166°, lightness 0.86 and chroma 0.14. It sits on the cool side of the color wheel. In practice it behaves as a mid-weight working color for secondary surfaces and editorial blocks.
| HEX | #66EEBB |
|---|---|
| RGB | rgb(102, 238, 187) |
| HSL | hsl(158, 80%, 67%) |
| HSV | hsv(158, 57%, 93%) |
| CMYK | cmyk(57%, 0%, 21%, 7%) |
| CIE Lab | lab(85.8 -49 13.7) |
| OKLCH | oklch(0.860 0.140 166) |
Under warm 2700K interior light Onsen shifts subtly: drifts toward green; in north-facing or shaded light it is virtually unchanged. Overall drift across common illuminants is small (max ΔE ≈ 2.2), so it is a lighting-stable choice.
#7ee8ae — ΔE 2.2, shifts subtly: drifts toward green#74efb7 — ΔE 1.1, shifts subtly: drifts toward green#66eebb — ΔE 0.0, is virtually unchanged#64efbe — ΔE 0.4, is virtually unchangedTest Onsen in the color lighting simulator — sweep it through daylight, warm 2700K light, 4000K LED, and shade alongside the rest of your palette.
Against white it measures 1.45:1 and against black 14.51:1, so black text is the stronger pairing. That pairing passes WCAG AA for body text. Avoid white text on this color entirely.
One color explored: close hues with real lightness and chroma structure, so the palette is the anchor through value rather than a set of colors.
#ceffe9 · #66eebb · #3dbb8f · #12926c · #006a4c · #00432f
The anchor's neighbours on the wheel — everything shares an undertone, so the chord carries color without anything having to be muted to get along.
#bdfeff · #71fbe6 · #66eebb · #7dd590 · #8cbb6b · #93a14e
The mid-gap pairing — sage and mustard, terracotta and olive. A foil rotated 40–65° toward warm or cool: too far to be kin, too near to argue, carried by temperature and a deliberate value offset.
#66eebb · #7cbdcf · #36a981 · #00829b · #00694b · #004554
One deliberately opposed voice — a single restrained counterpoint across the wheel, or temperature against temperature where the anchor is too muted to carry a loud opposite.
#66eebb · #cf6da7 · #557466 · #175a43 · #003b28 · #001c11
The anchor as the only color in the room. True neutrals or complement-warmed near-neutrals let it stay dominant.
#66eebb · #beafb7 · #6f847a · #52484e · #0d241b · #030001
This color as a ground rather than a subject — its own restraint held across a narrow value band, carrying one saturated voice from the opposite temperature.
#faeef4 · #d3c4cb · #a7969f · #2e1c26 · #0a0005 · #66eebb
The opposite hue on the perceptual wheel, tempered to field strength — warm/cool tension without vibration.
#e9efca · #66eebb · #9acb8c · #e237f5 · #403e68 · #120729
The complement's two neighbours instead of the complement itself — strong contrast with a lower clash risk.
#ffe6ca · #66eebb · #c3b5d7 · #d6708f · #4c3d56 · #081203
Three hues spaced evenly around the wheel; the anchor leads and the other two are held at supporting strength.
#66eebb · #b1b1cf · #7873be · #7d3100 · #381000 · #020010
Two complementary pairs offset by 90° — the richest chord, kept usable by a strict lightness hierarchy.
#66eebb · #a3b6cf · #4e80c0 · #7d215c · #2d1a00 · #070003
#7FF1C4 · #95F4CC · #A9F7D5 · #BBF9DD · #CDFCE6
#46C497 · #229B74 · #007453 · #004D36 · #002A1C
#85E8C0 · #9EE2C4 · #B3DCC9
Its moderate chroma lets it work in mid-size areas — upholstery, secondary UI surfaces, editorial blocks — without overwhelming neighbors. In palettes it pairs most predictably with its tonal ramp and analogous neighbors; reserve the complementary hue for small, deliberate contrast.