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Strong Knell Indigo

#5756f0
Notes

Strong Knell Indigo (#5756F0) 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 (240°, 84%, 64%) places it in the highly saturated band at a mid lightness. Best used in small doses, like logos, CTAs, focus rings, or highlight text, where its saturation becomes a feature rather than noise. For a confident two-color system, pair it with its complementary yellow. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#5756f0
RGB
rgb(87, 86, 240)
HSL
hsl(240, 84%, 64%)
HWB
hwb(240 34% 6%)
OKLCH
oklch(55.0% 0.224 276.4)
HSV
hsv(240, 64%, 94%)
LAB
lab(45.59% 46.00 -77.30)
LCH
lch(45.59% 89.96 300.75)
CMYK
cmyk(64%, 64%, 0%, 6%)

Etymology

Strong
adjective

Old English strang, firm, vigorous — applied to color since the sixteenth century. Strong red, strong tea: a color at full strength is the maximum saturation the medium can produce. Sits at the saturated mid corner of the grid, parallel to bold in usage but slightly more focused on pigment density than on assertion.

Knell
modifier

Old English cnyll, funeral-bell. As a color modifier, knell implies a funeral-and-passing-bell quality, the visual register of English-funeral-and-passing-bell slow-and-tolling-funeral mourning-bell-and-bell-tower-tolling slow-and-mourning surfaces under slow-tolling-funeral-bell mourning candlelight. Sits at the modifier-and-time end of the grid, parallel to bell and vesper in usage.

Indigo
noun

Indigofera tinctoria, the South Asian legume whose leaves yield the deep blue dye that has clothed humanity for at least four thousand years — Egyptian linen, Mayan textile, the slave-grown plantations of Carolina. The color refers to a freshly indigo-dyed cotton thread: a saturated, slightly violet-shifted deep blue with the slight lustre of a fiber surface oxidized in air. Deeper than cobalt, cooler than royal.

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

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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.

#5756f0
Original
#0073f5
Protanopia
#0065ed
Deuteranopia
#007e9b
Tritanopia
#616161
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
5.26:1
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
3.99:1

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