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Healthful Horus Lagoon

#21b5d9
Notes

Healthful Horus Lagoon (#21B5D9) is a true cyan with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (192°, 74%, 49%) 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 red. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#21b5d9
RGB
rgb(33, 181, 217)
HSL
hsl(192, 74%, 49%)
HWB
hwb(192 13% 15%)
OKLCH
oklch(71.7% 0.125 219.9)
P3
color(display-p3 0.3399 0.6995 0.8354)
HSV
hsv(192, 85%, 85%)
LAB
lab(68.30% -24.17 -28.48)
LCH
lch(68.30% 37.35 229.68)
CMYK
cmyk(85%, 17%, 0%, 15%)

Etymology

Healthful
adjective

Old English hǣlth, health — adjectival suffix -ful. As a color modifier, healthful implies a clear-and-vital-and-wholesome quality where the hue carries the visual register of fresh-air-and-sunlight outdoor health-promoting environment. Sits at the crisp-and-wholesome end of the grid, parallel to salubrious and wholesome in usage.

Horus
modifier

Egyptian Heru, falcon-headed-sky-god. As a color modifier, horus implies a falcon-headed-and-Eye-of-Horus quality, the visual register of Egyptian-Horus-and-Edfu-temple hand-falcon-headed-and-Eye-of-Horus Egyptian-Horus-and-Edfu-temple-and-falcon-pharaoh horus-and-falcon-headed-and-Eye-of-Horus surfaces under Egyptian-Horus-and-Edfu-temple-and-falcon-pharaoh Edfu-Aswan-temple-and-falcon-throne falcon-eye-light. Sits at the modifier-and-myth end of the grid, parallel to isis and thoth in usage.

Lagoon
noun

A shallow body of saltwater partially or fully enclosed by a barrier — coral atoll lagoons in the Pacific, Venice's Laguna Veneta, the Florida Keys' backcountry. The color refers to the average reflectance of a calm tropical lagoon at midday: a saturated, slightly muted blue-green with the optical clarity of shallow water over white sand. Brighter than reef, cooler than aquamarine, with the postcard weight of a Pacific atoll seen from above.

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.

#21b5d9
Original
#9fb0db
Protanopia
#889fd9
Deuteranopia
#00c1c1
Tritanopia
#989898
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).
Failon White
2.42:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AAAon Black
8.68:1

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
##21B5D9
Display P3
Display P3
color(display-p3 0.3399 0.6995 0.8354)
P3 has subtle headroomOKLCH chroma 0.125

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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