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Frank Sour Lagoon

#1fb4d3
Notes

Frank Sour Lagoon (#1FB4D3) 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 (190°, 74%, 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
#1fb4d3
RGB
rgb(31, 180, 211)
HSL
hsl(190, 74%, 47%)
HWB
hwb(190 12% 17%)
OKLCH
oklch(71.2% 0.122 216.8)
P3
color(display-p3 0.3359 0.6956 0.8132)
HSV
hsv(190, 85%, 83%)
LAB
lab(67.75% -25.78 -26.03)
LCH
lch(67.75% 36.64 225.27)
CMYK
cmyk(85%, 15%, 0%, 17%)

Etymology

Frank
adjective

From the Old French franc, free, sincere — used as a color modifier since the seventeenth century for hues that read as direct and unhedged. Frank red, frank brown: moderate-to-high saturation combined with optical directness. Sits at the crisp-bucket alongside direct and honest.

Sour
modifier

Old English sūr, acid-or-fermented. As a color modifier, sour implies a fermented-and-puckered-and-acid quality, the visual register of sourdough-and-Bavarian-sauerkraut-sour hand-fermented-and-puckered-and-acid sourdough-and-Bavarian-sauerkraut-sour-and-Belgian-Lambic sour-and-fermented-and-puckered surfaces under sourdough-and-Bavarian-sauerkraut-sour-and-Belgian-Lambic San-Francisco-sourdough-and-Brussels-Lambic fermented-puckered-light. Sits at the modifier-and-flavor end of the grid, parallel to tart and tang 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.

#1fb4d3
Original
#9faed5
Protanopia
#899ed3
Deuteranopia
#00bfbe
Tritanopia
#979797
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
2.46:1
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
8.53:1

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
##1FB4D3
Display P3
Display P3
color(display-p3 0.3359 0.6956 0.8132)
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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