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Substantial Rune Cerulean

#1d88d7
Notes

Substantial Rune Cerulean (#1D88D7) is a true azure with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (205°, 76%, 48%) 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 orange. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#1d88d7
RGB
rgb(29, 136, 215)
HSL
hsl(205, 76%, 48%)
HWB
hwb(205 11% 16%)
OKLCH
oklch(60.9% 0.150 247.1)
P3
color(display-p3 0.2572 0.5255 0.8191)
HSV
hsv(205, 87%, 84%)
LAB
lab(54.84% -0.34 -48.43)
LCH
lch(54.84% 48.43 269.59)
CMYK
cmyk(87%, 37%, 0%, 16%)

Etymology

Substantial
adjective

Latin substantia, substance — adjectival suffix -al, derived from sub-stāre (to stand under). As a color modifier, substantial implies a saturated-and-weighty-and-material quality where the hue carries visual mass and presence. Sits at the bold-and-weighty end of the grid, parallel to weighty and hefty in usage.

Rune
modifier

Old Norse rún, secret-or-runic-letter. As a color modifier, rune implies a Norse-runic-letter-and-Futhark-and-incised-stone quality, the visual register of Elder-Futhark-and-Norse-runic-stone hand-Norse-runic-letter-and-Futhark-and-incised-stone Elder-Futhark-and-Norse-runic-stone-and-Viking-grave-marker rune-and-Norse-runic-letter-and-Futhark surfaces under Elder-Futhark-and-Norse-runic-stone-and-Viking-grave-marker Jelling-stone-and-Rök-runestone runic-incision-light. Sits at the modifier-and-myth end of the grid, parallel to omen and sigil in usage.

Cerulean
noun

From the Latin caeruleum, originally referring to dark blue paint pigment of the Roman world, then via French céruléen into English. As a modern art-supply name, cerulean blue is the cobalt-tin oxide pigment introduced in 1805. The color refers to a clean, slightly green-shifted blue with the matte finish of mineral pigment in linseed oil: lighter than cobalt, deeper than aqua, with the painter's weight of a word for sky.

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.

#1d88d7
Original
#628cda
Protanopia
#467cd5
Deuteranopia
#009ba5
Tritanopia
#777777
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
3.78:1
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
5.56:1

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
##1D88D7
Display P3
Display P3
color(display-p3 0.2572 0.5255 0.8191)
P3 has subtle headroomOKLCH chroma 0.150

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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