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Sullen Jericho

#370f5a
Notes

Sullen Jericho (#370F5A) is a deep indigo with a jewel character. It carries the deep, saturated richness of a gemstone. Authoritative and slightly formal, it works well for type and heavy UI elements. Its HSL profile (272°, 71%, 21%) places it in the balanced band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. For a confident two-color system, pair it with its complementary lime. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#370f5a
RGB
rgb(55, 15, 90)
HSL
hsl(272, 71%, 21%)
HWB
hwb(272 6% 65%)
OKLCH
oklch(28.2% 0.124 303.2)
P3
color(display-p3 0.1973 0.0692 0.3391)
HSV
hsv(272, 83%, 35%)
LAB
lab(14.91% 34.55 -36.48)
LCH
lch(14.91% 50.24 313.44)
CMYK
cmyk(39%, 83%, 0%, 65%)

Etymology

Sullen
adjective

Old French solain, solitary via Anglo-French solein. As a color modifier, sullen implies a deep-and-cool-and-withholding quality, the dark cool-gray of Norwegian-fjord mid-winter atmospheric-overcast and saturated-saltwater-cliff in late-November light. Sits at the deep-and-cool end of the grid, parallel to gloomy and saturnine in atmospheric tone.

Jericho
noun

Ancient Levantine city (continuously occupied since 9000 BCE) — and a secondary Tyrian-purple production site supplying the inland Judean and Idumean courts. Jericho color refers to a Jericho-produced Tyrian-purple-dyed talith prayer shawl: a saturated, slightly cool deep violet with the matte finish of multi-bath Murex shellfish dye on Levantine wool. Slightly warmer than Tyre itself.

Closest matches

The nearest named color in three reference sources, ranked by perceptual distance (ΔE76 in CIELAB). ΔE < 1 is imperceptible to most viewers; ΔE > 10 is clearly different. When two sources point to the same hex they’re merged into one tile; click any to open that color’s page.

Variations

Click any swatch to explore

Harmonies

Accessibility

Color-vision simulation

How this color appears to viewers with the four major color-vision-deficiency types. Computed via the Machado (2009) physiologically-based model. If a tile matches the original, the color reads the same to that viewer.

#370f5a
Original
#00255c
Protanopia
#002559
Deuteranopia
#302334
Tritanopia
#1d1d1d
Achromatopsia
WCAG contrast

The color used as foreground text against pure white and pure black, with the contrast ratio and WCAG 2.1 grade. Aim for AA (4.5:1) for body text and AA Large (3:1) for 18 pt+ headlines; AAA (7:1) is the gold standard for long-form reading surfaces.

The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAAon White
15.23:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
Failon Black
1.38:1

Wide gamut

Display P3 representation

The CSS Color 4 wide-gamut form of this color. Both swatches render the same color on every display — the P3 form only diverges from sRGB when a designer pushes channels outside sRGB's reach.

sRGB hex
sRGB hex
##370F5A
Display P3
Display P3
color(display-p3 0.1973 0.0692 0.3391)
P3 has subtle headroomOKLCH chroma 0.124

Moderately saturated colors gain a small bump in P3 — the difference is usually visible side-by-side on wide-gamut hardware but won't change the character of the color.

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