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Open Foil Lagoon

#39bdd9
Notes

Open Foil Lagoon (#39BDD9) 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 (191°, 68%, 54%) 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
#39bdd9
RGB
rgb(57, 189, 217)
HSL
hsl(191, 68%, 54%)
HWB
hwb(191 22% 15%)
OKLCH
oklch(74.0% 0.117 215.4)
P3
color(display-p3 0.3871 0.7310 0.8375)
HSV
hsv(191, 74%, 85%)
LAB
lab(71.06% -25.95 -24.21)
LCH
lch(71.06% 35.49 223.01)
CMYK
cmyk(74%, 13%, 0%, 15%)

Etymology

Open
adjective

Old English open, unobstructed — used as a color modifier since the eighteenth century for hues that read as airy or uncrowded. Open blue, open green: moderate saturation combined with optical spaciousness, the slight visual breath of a hue that doesn't crowd the surface it covers. Sits at the crisp-bucket center alongside clear.

Foil
modifier

Old French fueille, leaf. As a color modifier, foil implies a thin-rolled-metal-leaf quality, the visual register of hand-rolled-and-beaten-foil hand-rolled-and-beaten-thin gold-and-silver-and-tin-foil hand-rolled-and-beaten-thin-foil surfaces under hand-rolled-and-beaten-foil workshop-light. Sits at the modifier-and-texture end of the grid, parallel to gold and gilt 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.

#39bdd9
Original
#aab7db
Protanopia
#94a7d9
Deuteranopia
#00c7c6
Tritanopia
#a3a3a3
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
2.22:1
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
9.45:1

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
##39BDD9
Display P3
Display P3
color(display-p3 0.3871 0.7310 0.8375)
P3 has subtle headroomOKLCH chroma 0.117

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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