Steadfast Nocturne
Steadfast Nocturne (#5758E5) is a true blue with a vibrant character. It holds its own as a focal accent, carrying visual weight without tipping into neon territory. Its HSL profile (240°, 73%, 62%) 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 yellow. For something softer, pull in its analogous neighbors on either side of the wheel.
Etymology
Old English stede-fæst, fixed in place — sharing root with German stetig. As a color modifier, steadfast implies a saturated-and-unwavering quality where the hue maintains its visual character without modulation. Sits at the bold-and-firm end of the grid, parallel to unwavering and firm in usage.
French nocturne, night-piece — adopted into music by John Field (Irish, 1812) and Frédéric Chopin (Polish, 1827–46) for piano character pieces evoking nighttime, and into painting by James McNeill Whistler for a series of deep-blue-violet Thames-river twilights. Nocturne color refers to a Whistler Nocturne in Black and Gold foreground tonality: a saturated, slightly cool deep blue-violet with the soft finish of thinned oil over warm gesso.
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 exploreHarmonies
Accessibility
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.
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.
Wide gamut
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.
This color is chromatic enough that authoring it as P3 native (instead of clamping to sRGB) gives a perceptibly more saturated render on wide-gamut displays — modern Macs, iPhones, iPads, and most recent OLED laptops.