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Strong Rime Indigo

#646ee0
Notes

Strong Rime Indigo (#646EE0) 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 (235°, 67%, 64%) 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 yellow. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#646ee0
RGB
rgb(100, 110, 224)
HSL
hsl(235, 67%, 64%)
HWB
hwb(235 39% 12%)
OKLCH
oklch(58.8% 0.171 276.0)
P3
color(display-p3 0.3995 0.4301 0.8501)
HSV
hsv(235, 55%, 88%)
LAB
lab(50.97% 28.60 -59.54)
LCH
lch(50.97% 66.05 295.66)
CMYK
cmyk(55%, 51%, 0%, 12%)

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.

Rime
modifier

Old English hrīm, hoar-frost-on-twigs. As a color modifier, rime implies a feathered-frost-and-fog-deposited quality, the visual register of Scottish-Highland-and-Cairngorm-rime hand-feathered-frost-and-fog-deposited Scottish-Highland-and-Cairngorm-rime-and-Pennine-cap rime-and-feathered-frost-and-fog-deposited surfaces under Scottish-Highland-and-Cairngorm-rime-and-Pennine-cap Cairngorm-Highlands-and-Scottish-Munro-and-Pennine-cap freezing-fog-light. Sits at the modifier-and-weather end of the grid, parallel to hoar and sleet 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

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.

#646ee0
Original
#317fe4
Protanopia
#1b74de
Deuteranopia
#20889d
Tritanopia
#747474
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).
AA Largeon White
4.33:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAon Black
4.85:1

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
##646EE0
Display P3
Display P3
color(display-p3 0.3995 0.4301 0.8501)
P3 has subtle headroomOKLCH chroma 0.171

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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