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Submersed Slate

#21358f
Notes

Submersed Slate (#21358F) is a true blue 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 (229°, 63%, 35%) 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
#21358f
RGB
rgb(33, 53, 143)
HSL
hsl(229, 63%, 35%)
HWB
hwb(229 13% 44%)
OKLCH
oklch(37.5% 0.150 268.4)
HSV
hsv(229, 77%, 56%)
LAB
lab(26.31% 25.78 -52.01)
LCH
lch(26.31% 58.05 296.36)
CMYK
cmyk(77%, 63%, 0%, 44%)

Etymology

Submersed
adjective

Latin sub-mersus, plunged-under — past-participle of submerse. As a color modifier, submersed implies the deep-saturated-and-cool-shifted quality of a hue viewed through a layer of water, like an underwater coral-reef object seen from a glass-bottomed boat. Sits at the deep-and-cool end of the grid, parallel to submerged with slightly-archaic register.

Slate
noun

A fine-grained metamorphic rock formed from compressed shale — fissile, durable, and the standard roofing material for Welsh and Vermont houses since the nineteenth century. The color refers to a freshly split piece of Welsh slate: a soft, slightly muted gray-blue with the matte finish of a layered mineral cleavage. Cooler than steel, lighter than navy, with the architectural weight of a roof material that lasts a hundred years.

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.

#21358f
Original
#004492
Protanopia
#00398d
Deuteranopia
#004c5c
Tritanopia
#373737
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
10.66:1
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
1.97:1

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