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Reposeful Scud Lagoon

#21bcd5
Notes

Reposeful Scud Lagoon (#21BCD5) 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 (188°, 73%, 48%) 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
#21bcd5
RGB
rgb(33, 188, 213)
HSL
hsl(188, 73%, 48%)
HWB
hwb(188 13% 16%)
OKLCH
oklch(73.2% 0.122 212.2)
P3
color(display-p3 0.3522 0.7265 0.8224)
HSV
hsv(188, 85%, 84%)
LAB
lab(70.24% -28.97 -23.31)
LCH
lch(70.24% 37.19 218.82)
CMYK
cmyk(85%, 12%, 0%, 16%)

Etymology

Reposeful
adjective

Latin repōnere, to put back — adjectival suffix -ful. As a color modifier, reposeful implies a clear-and-restful-and-still quality, the calm color of pre-modern monastic cloister-and-refectory meditative-and-silent interior architecture. Sits at the crisp-and-calm end of the grid, parallel to peaceful and placid in usage.

Scud
modifier

Origin obscure, low-fast-driven-cloud. As a color modifier, scud implies a low-fast-driven-cloud-and-storm-front quality, the visual register of North-Sea-and-Cornish-coast-scud hand-low-fast-driven-cloud-and-storm-front North-Sea-and-Cornish-coast-scud-and-Atlantic-front-cloud scud-and-low-fast-driven-cloud surfaces under North-Sea-and-Cornish-coast-scud-and-Atlantic-front-cloud Lizard-Point-and-Outer-Hebrides storm-front-cloud-light. Sits at the modifier-and-weather end of the grid, parallel to gust and mistral 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.

#21bcd5
Original
#a9b5d6
Protanopia
#92a5d5
Deuteranopia
#00c6c4
Tritanopia
#9d9d9d
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
2.28:1
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
9.22:1

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
##21BCD5
Display P3
Display P3
color(display-p3 0.3522 0.7265 0.8224)
P3 has subtle headroomOKLCH chroma 0.122

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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