#665A51Underground (#665A51) is a grey neutral with an OKLCH hue of 59°, lightness 0.48 and chroma 0.021. In practice it behaves as a mid-weight working color for secondary surfaces and editorial blocks.
| HEX | #665A51 |
|---|---|
| RGB | rgb(102, 90, 81) |
| HSL | hsl(26, 11%, 36%) |
| HSV | hsv(26, 21%, 40%) |
| CMYK | cmyk(0%, 12%, 21%, 60%) |
| CIE Lab | lab(39.1 3.2 7) |
| OKLCH | oklch(0.476 0.021 59) |
Under warm 2700K interior light Underground shifts subtly: takes on a orange cast; in north-facing or shaded light it is virtually unchanged. Overall drift across common illuminants is small (max ΔE ≈ 1.1), so it is a lighting-stable choice.
#69574b — ΔE 1.1, shifts subtly: takes on a orange cast#695a4f — ΔE 0.6, is virtually unchanged#665a51 — ΔE 0.0, is virtually unchanged#665a52 — ΔE 0.2, is virtually unchangedTest Underground 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 6.67:1 and against black 3.15:1, so white text is the stronger pairing. That pairing passes WCAG AA for body text.
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.
#b8aea6 · #93877f · #665a51 · #4c4139 · #2b221b · #0e0703
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.
#8c7e56 · #846840 · #665a51 · #6c3f2c · #592e2a · #451f26
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.
#b7b99b · #999c65 · #7a7c62 · #665a51 · #5a391c · #3d2004
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.
#79acd0 · #87796f · #665a51 · #4f3a29 · #311f10 · #120802
The anchor as the only color in the room. True neutrals or complement-warmed near-neutrals let it stay dominant.
#ecf3f8 · #bab0a9 · #72777b · #665a51 · #4c423b · #000102
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.
#f6f1ed · #cfc8c4 · #665a51 · #2c241e · #0a0402 · #f29644
The opposite hue on the perceptual wheel, tempered to field strength — warm/cool tension without vibration.
#e5f4ff · #8fb8d5 · #4a7d9e · #665a51 · #1f4862 · #120400
The complement's two neighbours instead of the complement itself — strong contrast with a lower clash risk.
#e5f4ff · #85bdc7 · #6475a3 · #665a51 · #084d56 · #000008
Three hues spaced evenly around the wheel; the anchor leads and the other two are held at supporting strength.
#e3f7f2 · #88bfb3 · #7c6c9d · #665a51 · #493c61 · #000302
Two complementary pairs offset by 90° — the richest chord, kept usable by a strict lightness hierarchy.
#e8f6ea · #98bd9e · #4a7d9e · #665a51 · #573755 · #00050f
#7D7269 · #948A83 · #ACA49D · #C5BEB9 · #DED9D5
#554A42 · #453B34 · #352D27 · #261F1A · #18120D
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.