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Rugged Kachi

#3757dd
Notes

Rugged Kachi (#3757DD) is a true blue with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (228°, 71%, 54%) places it in the balanced band at a mid lightness. It works across type, buttons, and borders, saturated enough to feel deliberate but balanced enough to not fight the rest of the palette. For a confident two-color system, pair it with its complementary amber. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#3757dd
RGB
rgb(55, 87, 221)
HSL
hsl(228, 71%, 54%)
HWB
hwb(228 22% 13%)
OKLCH
oklch(51.8% 0.207 267.9)
P3
color(display-p3 0.2436 0.3379 0.8356)
HSV
hsv(228, 75%, 87%)
LAB
lab(42.53% 35.00 -71.63)
LCH
lch(42.53% 79.73 296.04)
CMYK
cmyk(75%, 61%, 0%, 13%)

Etymology

Rugged
adjective

Old Norse rugga, rough / coarse — adjectival suffix -ed. As a color modifier, rugged implies a saturated-and-rough-and-weathered quality, the deep-rich color of Scottish-Highlands-and-Norwegian-fjord outdoor-and-mountain landscape. Sits at the bold-and-weathered end of the grid, parallel to tough and sinewy in usage.

Kachi
noun

Japanese kachi-iro (褐色 or 勝色) — victory color, the deep blue-black favored by samurai for ceremonial dress because kachi phonetically equals victory. The deepest indigo dye, often applied through six or seven dye baths. The color refers to a kachi-dyed samurai jinbaori: a saturated, slightly cool very deep blue-black with the matte finish of multi-bath indigo silk.

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.

#3757dd
Original
#006ce1
Protanopia
#005dda
Deuteranopia
#007992
Tritanopia
#5a5a5a
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).
AAon White
5.88:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AA Largeon Black
3.57:1

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
##3757DD
Display P3
Display P3
color(display-p3 0.2436 0.3379 0.8356)
P3 has visible headroomOKLCH chroma 0.207

This color is chromatic enough that authoring it as P3 native (instead of clamping to sRGB) gives a perceptibly more saturated render on wide-gamut displays — modern Macs, iPhones, iPads, and most recent OLED laptops.

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