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Placid Terra Lagoon

#21b6ce
Notes

Placid Terra Lagoon (#21B6CE) 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°, 72%, 47%) 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
#21b6ce
RGB
rgb(33, 182, 206)
HSL
hsl(188, 72%, 47%)
HWB
hwb(188 13% 19%)
OKLCH
oklch(71.5% 0.119 212.0)
P3
color(display-p3 0.3416 0.7033 0.7954)
HSV
hsv(188, 84%, 81%)
LAB
lab(68.19% -28.27 -22.60)
LCH
lch(68.19% 36.19 218.65)
CMYK
cmyk(84%, 12%, 0%, 19%)

Etymology

Placid
adjective

Latin placidus, gentle / quiet — derived from placēre (to please). As a color modifier, placid implies a clear-and-unruffled quality where the hue carries the visual register of mirror-smooth lake-surface in windless mid-morning. Sits at the crisp-and-calm end of the grid, parallel to serene and peaceful in usage.

Terra
modifier

Latin terra, earth-or-land. As a color modifier, terra implies a earth-globe-and-loamy-and-grounded quality, the visual register of Pale-Blue-Dot-and-Apollo-Terra hand-earth-globe-and-loamy-and-grounded Pale-Blue-Dot-and-Apollo-and-Earthrise terra-and-earth-globe-and-loamy-and-grounded surfaces under Pale-Blue-Dot-and-Apollo-and-Earthrise lunar-orbit-and-deep-space earth-globe-light. Sits at the modifier-and-cosmic end of the grid, parallel to luna and sol 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.

#21b6ce
Original
#a3afcf
Protanopia
#8d9fce
Deuteranopia
#00c0bd
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
2.43:1
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
8.65:1

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
##21B6CE
Display P3
Display P3
color(display-p3 0.3416 0.7033 0.7954)
P3 has subtle headroomOKLCH chroma 0.119

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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