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Strong Dux Royal

#3f6bdb
Notes

Strong Dux Royal (#3F6BDB) is a true azure with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (223°, 68%, 55%) 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 amber. For something softer, pull in its analogous neighbors on either side of the wheel.

HEX
#3f6bdb
RGB
rgb(63, 107, 219)
HSL
hsl(223, 68%, 55%)
HWB
hwb(223 25% 14%)
OKLCH
oklch(55.9% 0.178 265.0)
P3
color(display-p3 0.2870 0.4152 0.8303)
HSV
hsv(223, 71%, 86%)
LAB
lab(47.86% 22.58 -61.82)
LCH
lch(47.86% 65.82 290.06)
CMYK
cmyk(71%, 51%, 0%, 14%)

Etymology

Strong
adjective

Old English strang, firm, vigorous — applied to color since the sixteenth century. Strong red, strong tea: a color at full strength is the maximum saturation the medium can produce. Sits at the saturated mid corner of the grid, parallel to bold in usage but slightly more focused on pigment density than on assertion.

Dux
modifier

Latin dux, leader-or-general. As a color modifier, dux implies a Latin-leader-and-Roman-general-and-Doge quality, the visual register of Roman-dux-and-Venetian-Doge hand-Latin-leader-and-Roman-general-and-Doge Roman-dux-and-Venetian-Doge-and-Renaissance-condottiere dux-and-Latin-leader surfaces under Roman-dux-and-Venetian-Doge-and-Renaissance-condottiere Republican-Rome-and-Venetian-Doge's-Palace leader-and-general-light. Sits at the modifier-and-Latin end of the grid, parallel to pater and virtus in usage.

Royal
noun

The blue of European royal court dress and regalia from the late seventeenth century forward — the color of British peers' robes, French royal sashes, the lining of the crown-jewel cases. The color refers to a saturated, slightly violet-shifted blue with the matte finish of velvet or melton wool dyed to maximum intensity: deeper than cornflower, warmer than ultramarine, with the heraldic weight of a color reserved for monarchs and the official Crown.

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.

#3f6bdb
Original
#2379df
Protanopia
#006bd9
Deuteranopia
#008699
Tritanopia
#6a6a6a
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
4.84:1
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
4.34:1

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
##3F6BDB
Display P3
Display P3
color(display-p3 0.2870 0.4152 0.8303)
P3 has subtle headroomOKLCH chroma 0.178

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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