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Stable Plasma Lagoon

#40b1c9
Notes

Stable Plasma Lagoon (#40B1C9) is a true cyan with a cool character. It leans cool, sitting on the blue, green, and violet side of the wheel. Quiet and dependable, a fit for product UI and data visualization. Its HSL profile (191°, 56%, 52%) 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
#40b1c9
RGB
rgb(64, 177, 201)
HSL
hsl(191, 56%, 52%)
HWB
hwb(191 25% 21%)
OKLCH
oklch(70.7% 0.105 214.6)
P3
color(display-p3 0.3814 0.6849 0.7764)
HSV
hsv(191, 68%, 79%)
LAB
lab(67.09% -23.97 -21.48)
LCH
lch(67.09% 32.18 221.87)
CMYK
cmyk(68%, 12%, 0%, 21%)

Etymology

Stable
adjective

Latin stabilis, standing-firm — sharing root with stand. As a color modifier, stable implies a clear-and-firm-and-unchanging quality where the hue carries the visual register of resistant-to-modulation-and-fade pigmentation. Sits at the crisp-and-firm end of the grid, parallel to steady and settled in usage.

Plasma
modifier

Greek πλάσμα, something-molded-or-formed. As a color modifier, plasma implies an ionized-and-fourth-state-and-stellar-glow quality, the visual register of solar-corona-and-fluorescent-plasma hand-ionized-and-fourth-state-and-stellar-glow solar-corona-and-fluorescent-and-neon-tube plasma-and-ionized-and-fourth-state surfaces under solar-corona-and-fluorescent-and-neon-tube laboratory-and-stellar-and-aurora ionized-glow-light. Sits at the modifier-and-cosmic end of the grid, parallel to corona and nova 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.

#40b1c9
Original
#a0abca
Protanopia
#8c9dc9
Deuteranopia
#00bab8
Tritanopia
#9b9b9b
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
2.51:1
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
8.35:1

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
##40B1C9
Display P3
Display P3
color(display-p3 0.3814 0.6849 0.7764)
P3 has subtle headroomOKLCH chroma 0.105

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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