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Warm Phase Robin

#21707a
Notes

Warm Phase Robin (#21707A) is a deep 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 (187°, 57%, 30%) places it in the balanced band at a dark lightness. It works well as a headline, icon, or deep background in an otherwise light layout, pairing cleanly with cream, bone, and warm neutrals. 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
#21707a
RGB
rgb(33, 112, 122)
HSL
hsl(187, 57%, 30%)
HWB
hwb(187 13% 52%)
OKLCH
oklch(50.3% 0.075 207.3)
P3
color(display-p3 0.2245 0.4330 0.4722)
HSV
hsv(187, 73%, 48%)
LAB
lab(43.24% -19.81 -12.42)
LCH
lch(43.24% 23.38 212.08)
CMYK
cmyk(73%, 8%, 0%, 52%)

Etymology

Warm
adjective

Old English wearm, of moderate heat — used as a color modifier since the medieval period for hues that read as containing red, orange, or yellow undertones. Warm gray, warm white: not necessarily a temperature, but the optical impression of a slight red-orange shift. Sits across the crisp and neutral buckets.

Phase
modifier

Greek phásis, appearance / phase-of-the-moon. As a color modifier, phase implies a moon-phase-and-cycle-stage quality, the visual register of lunar-and-tidal-cycle moon-phase-and-tidal-rhythm waxing-and-waning lunar-cycle surfaces under waxing-and-waning lunar-cycle light. Sits at the modifier-and-time end of the grid, parallel to cycle and wane in usage.

Robin
noun

The American robin (Turdus migratorius) — though the color refers not to the bird's red breast but to the egg, robin's-egg blue, a pale slightly green-shifted blue produced by biliverdin pigment in the eggshell. The color is the inside surface of a fresh robin's nest at peak laying: a soft, slightly green-shifted pale blue with the matte finish of avian eggshell. Lighter than aqua, cooler than turquoise.

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.

#21707a
Original
#666b7b
Protanopia
#59627a
Deuteranopia
#007573
Tritanopia
#606060
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).
AAon White
5.73:1
The quick brown foxSample body text at normal size. The wcag minimum for body contrast is 4.5:1 (AA) or 7:1 (AAA).
AA Largeon Black
3.66:1

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
##21707A
Display P3
Display P3
color(display-p3 0.2245 0.4330 0.4722)
Inside sRGBOKLCH chroma 0.075

This color sits well within the sRGB cube. P3 and sRGB share the gray axis and most desaturated tones, so a P3 display renders this identically to an sRGB display.

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