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Sure Cowl Lagoon

#03b8d0
Notes

Sure Cowl Lagoon (#03B8D0) 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 (187°, 97%, 41%) places it in the highly saturated band at a mid lightness. Best used in small doses, like logos, CTAs, focus rings, or highlight text, where its saturation becomes a feature rather than noise. 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
#03b8d0
RGB
rgb(3, 184, 208)
HSL
hsl(187, 97%, 41%)
HWB
hwb(187 1% 18%)
OKLCH
oklch(71.8% 0.124 211.2)
P3
color(display-p3 0.3243 0.7107 0.8031)
HSV
hsv(187, 99%, 82%)
LAB
lab(68.64% -29.95 -23.03)
LCH
lch(68.64% 37.78 217.56)
CMYK
cmyk(99%, 12%, 0%, 18%)

Etymology

Sure
adjective

Old French seur, certain — used as a color modifier since the medieval period for hues that read as confident and stable. Sure red, sure blue: moderate saturation combined with optical commitment. Sits at the crisp-bucket center alongside steady and true.

Cowl
modifier

Latin cuculla, monk's-hood-or-hood-of-habit. As a color modifier, cowl implies a monk's-hood-and-deeply-folded-hood quality, the visual register of Benedictine-and-Cistercian-monk's-cowl hand-monk's-hood-and-deeply-folded-hood Benedictine-and-Cistercian-monk's-cowl-and-Cluny-Abbey cowl-and-monk's-hood surfaces under Benedictine-and-Cistercian-monk's-cowl-and-Cluny-Abbey Cluny-and-Cîteaux-Abbey monastic-cloister-light. Sits at the modifier-and-textile end of the grid, parallel to cloak and frock 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.

#03b8d0
Original
#a5b1d1
Protanopia
#8ea0d0
Deuteranopia
#00c2bf
Tritanopia
#939393
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
2.39:1
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
8.77:1

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
##03B8D0
Display P3
Display P3
color(display-p3 0.3243 0.7107 0.8031)
P3 has subtle headroomOKLCH chroma 0.124

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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