CSS named color
Blue #0000FF
Blue is vivid blue. Below: every color format, WCAG contrast against black and white, its tints, shades and tones, and the harmonies that pair with it.
Color values
Contrast & accessibility
WCAG contrast ratio of Blue used as a foreground on white and black backgrounds.
On white
On black
Tints, shades & tones
Systematic variations of Blue — click any swatch to copy its hex.
Simulated colour vision
How Blue reads under the four common colour-vision deficiencies, using the standard Machado (2009) matrices at full severity. A simulation, not a measurement of any one person's vision; the point is whether this colour still does its job when hue drops out.
#0000FFTailwind-style ramp
Eleven steps from 50 to 950 with the hue and saturation of Blue held and only lightness stepped. Computed, not curated: the 500 step sits closest to the source, which is where Tailwind puts a brand colour.
Color harmonies
Palettes built from Blue by rotating its hue. Each swatch links to its closest named color.
Complementary
Split-complementary
Use Blue in your stack
Tailwind (arbitrary value)
Works for any property: text-[#0000ff], border-[#0000ff].
CSS custom property
Reference it anywhere with var(--color).
Build a full theme
Turn Blue into a complete shadcn/ui palette — light & dark, contrast-checked, one-command install.
Extract a theme →