Tailwind CSS v3 color

Tailwind slate-900 #0F172A

Tailwind CSS v3's slate-900 is #0F172A. It is a very dark grayish blue in the blue family. In OKLCH it sits at lightness 0.208, chroma 0.040 and hue 265.8°. The nearest CSS named color is black (#000000), ΔE2000 12.1 away.

Relative luminance: 0.0088
OKLCH L · C · h: 0.208 · 0.040 · 265.8
Best text: White 17.85:1
Hue family: Blue

Inspect this color Check contrast

#0F172A color codes

HEX: #0F172A
RGB: rgb(15, 23, 42)
HSL: hsl(222, 47%, 11%)
OKLCH: oklch(0.208 0.040 265.8)
OKLab: oklab(0.208 -0.003 -0.040)
CIELAB (D65): L* 7.96, a* 3.32, b* -14.07
XYZ (D65): X 0.92, Y 0.88, Z 2.31
CMYK (naive): cmyk(64%, 45%, 0%, 84%)

CIELAB and XYZ use the D65 white point; CSS lab() uses D50, so paste the OKLCH or HEX value into stylesheets. CMYK here is a plain formula with no press profile.

Legibility

Contrast: is #0F172A accessible?

White text on it reaches 17.85:1, passing AAA. Black text fails at 1.17:1.

WCAG 2 gives the same ratio whichever color is the text; APCA does not, so its Lc changes sign and size with polarity.

Open the Contrast System

Black text on it

1.17:1
- AA fails
- AA large fails
- AAA fails
- APCA Lc 0
Text is here, unreadable at 1.17:1
White text on it

17.85:1
- AA passes
- AA large passes
- AAA passes
- APCA Lc −106
As text on black

1.17:1
- AA fails
- AA large fails
- AAA fails
- APCA Lc 0
Text is here, unreadable at 1.17:1
As text on white

17.85:1
- AA passes
- AA large passes
- AAA passes
- APCA Lc +104

Nearest versions that pass 4.5:1

For text on white

#0F172A 17.85:1

It already reaches 17.85:1 on white, so no change is needed.
For text on black

#6A758D 4.54:1

Lightening its OKLCH lightness from 0.21 to 0.56 reaches 4.54:1 on black, keeping the hue.

Compare both in the Contrast System

Checking another pair? Use the Contrast Checker.

Studio

Adjust #0F172A live

Move lightness, chroma and hue in OKLCH, or drag on the map. The map is every lightness and chroma at the current hue: sRGB inside the solid area, Display P3 out to the dashed line.

The studio needs JavaScript.

Scale

Shades and tints of #0F172A

Eleven OKLCH lightness steps at this hue, each with its contrast against white and black. #0F172A sits at step 950.

50#F1F5FF

White
1.09
Black
19.24
100#E2EBFF

White
1.19
Black
17.56
200#CDD8EF

White
1.43
Black
14.66
300#B2BED7

White
1.86
Black
11.23
400#96A2BB

White
2.56
Black
8.18
500#7B869F

White
3.65
Black
5.75
600#646F86

White
5.04
Black
4.15
700#4E586E

White
7.13
Black
2.94
800#364054

White
10.40
Black
2.01
900#21293A

White
14.55
Black
1.44
950This color#0F172A

White
17.85
Black
1.17

Under each step, white and black text on it; a bold figure passes 4.5:1.

Tailwind CSS v3 slate scale

The real Tailwind palette, for comparison with the computed ramp above.

50#F8FAFC
White
1.04
Black
20.07
100#F1F5F9
White
1.09
Black
19.16
200#E2E8F0
White
1.23
Black
17.03
300#CBD5E1
White
1.48
Black
14.14
400#94A3B8
White
2.56
Black
8.19
500#64748B
White
4.75
Black
4.41
600#475569
White
7.57
Black
2.77
700#334155
White
10.35
Black
2.02
800#1E293B
White
14.62
Black
1.43
900This color#0F172A

White
17.85
Black
1.17
950#020617
White
20.17
Black
1.04

Gamut

How vivid #0F172A can get

At its lightness and hue, sRGB reaches OKLCH chroma 0.142; #0F172A uses 28% of it. Display P3 reaches no further at this hue.

sRGB
Display P3
Rec. 2020
Dominant wavelength

OKLCH chroma: 0.040
sRGB edge: 0.142
Display P3 edge: 0.142
Rec. 2020 edge: 0.151
Dominant wavelength: 473 nm
Excitation purity: 45%
Chromaticity: x 0.2239, y 0.2142

This color#0F172A
Most vivid in sRGB#030057
Most vivid in Display P3oklch(0.208 0.142 265.8)

On a screen without Display P3 the last tile shows the sRGB edge instead.

Use the wider color where screens show it

.accent {
  color: #0f172a;
}
@media (color-gamut: p3) {
  .accent { color: color(display-p3 0.0079 0 0.3264); }
}

Mixing

Mixing #0F172A

Each row is the same mix worked out in a different space, with the halfway color at its end. sRGB, which older CSS gradients use, can sag gray or dark in the middle; OKLab keeps the lightness steps even; OKLCH holds chroma and hue as it goes.

White #FFFFFF

sRGB50%#878B95
OKLab50%#7C818E
OKLCH50%#7C818E

Black #000000

sRGB50%#080C15
OKLab50%#02040A
OKLCH50%#02040A

Its complement #201601

sRGB50%#181716
OKLab50%#181818
OKLCH50%#260F18

In CSS

/* A gradient and a mix, worked out in OKLCH */
background: linear-gradient(in oklch, #0f172a, white);
color: color-mix(in oklch, #0f172a 50%, white);

In use

#0F172A in an interface

A button, a link, a heading, a focused field, an icon and a chart line in this color, on a light page and a dark one. Each check is a WCAG 2 contrast minimum: 1.4.3 for text, 1.4.11 for the rest.

Light page

Button labelText, 4.5:117.85:1 Passes
Link and body-size textText, 4.5:117.85:1 Passes
Large headingLarge text, 3:117.85:1 Passes
Icons, borders and focus ringsNon-text, 3:117.85:1 Passes

Dark page

Button labelText, 4.5:117.85:1 Passes
Link and body-size textText, 4.5:11.04:1 Fails
Large headingLarge text, 3:11.04:1 Fails
Icons, borders and focus ringsNon-text, 3:11.04:1 Fails

For text on this page, the nearest shade that passes is #717D95 4.52:1

Color vision

How #0F172A looks with color blindness

Tritanopia changes it most, ΔE2000 14.1; deuteranopia changes it least, 0.6.

Simulated with Machado et al. (2009) at full severity, in linear light.

Simulate a whole page What each type sees

Protanopia

No working red (long-wavelength) cones

#10192B ΔE2000 1.2

Very close

Reads as very dark grayish blue
Deuteranopia

No working green (medium-wavelength) cones

#0D162A ΔE2000 0.6

Imperceptible

Reads as very dark grayish blue
Tritanopia

No working blue (short-wavelength) cones

#041B1E ΔE2000 14.1

Distinct

Reads as very dark grayish teal
Achromatopsia

No cone color vision; lightness only

#171717 ΔE2000 11.2

Distinct

Reads as near-black

Pairing check

Checked against its complement, #201601. Their lightness contrast is only 1.00:1, so where hue collapses, add a label, icon or pattern.

Vision	The pair	ΔE2000	Verdict
Normal vision	#0F172A · #201601	20.4	Stays distinct
Protanopia	#10192B · #1A1600	20.7	Stays distinct
Deuteranopia	#0D162A · #1D1902	23.0	Stays distinct
Tritanopia	#041B1E · #241311	23.7	Stays distinct
Achromatopsia	#171717 · #171717	0.0	Easily confused

Harmony

Color harmonies for #0F172A

Its complement is #201601, a very dark grayish brown, on the warm side of the wheel.

Hue rotations in OKLCH, mapped into sRGB by trimming chroma so hue and lightness stay put.

Open the Harmony Studio

Base#0F172A
Complement#201601

Complementary

Open in Harmony Studio

−30°#031A27
Base#0F172A
+30°#191428

Analogous

Open in Harmony Studio

Base#0F172A
+120°#27100E
+240°#0B1D0C

Triadic

Open in Harmony Studio

Base#0F172A
+150°#251205
+210°#171A04

Split-complementary

Open in Harmony Studio

Code

Design tokens

Ready-to-paste tokens in six formats. Rename them to fit your system.

CSS custom property

:root {
  --color-slate-900: #0f172a;
}

Tailwind config

// tailwind.config.js — already built in as slate-900;
// pin the v3 value explicitly like this:
module.exports = {
  theme: {
    extend: {
      colors: {
        slate: { 900: '#0f172a' },
      },
    },
  },
};

Tailwind v4 theme

/* app.css — Tailwind CSS v4 */
@import "tailwindcss";

@theme {
  /* v4 has its own slate-900; this pins the v3 value. */
  --color-slate-900: oklch(0.208 0.040 265.8);
}

Design token (W3C DTCG)

{
  "color": {
    "slate-900": {
      "$type": "color",
      "$value": {
        "colorSpace": "srgb",
        "components": [0.0588, 0.0902, 0.1647],
        "hex": "#0f172a"
      },
      "$description": "Tailwind CSS v3 slate-900"
    }
  }
}

SwiftUI color

import SwiftUI

enum Palette {
    static let slate900 = Color(.sRGB, red: 0.059, green: 0.090, blue: 0.165, opacity: 1)
}

Jetpack Compose color

import androidx.compose.ui.graphics.Color

object Palette {
    val Slate900 = Color(0xFF0F172A)
}

Matches

The nearest match in each system

The closest CSS name, Tailwind shade, RAL Classic paint and Crayola crayon by ΔE2000; under 2 is hard to tell apart side by side. RAL and Crayola values approximate physical colors.

Tools

Open #0F172A in the tools

Each opens over this page. More colors live in the Color Library, and every color page is listed on the hub.

Tailwind slate-900 #0F172A

#0F172A color codes

Contrast: is #0F172A accessible?

Black text on it

White text on it

As text on black

As text on white

Nearest versions that pass 4.5:1

Adjust #0F172A live

Shades and tints of #0F172A

Tailwind CSS v3 slate scale

How vivid #0F172A can get

Mixing #0F172A

#0F172A in an interface

How #0F172A looks with color blindness

Protanopia

Deuteranopia

Tritanopia

Achromatopsia

Pairing check

Color harmonies for #0F172A

Complementary

Analogous

Triadic

Split-complementary

Design tokens

CSS custom property

Tailwind config

Tailwind v4 theme

Design token (W3C DTCG)

SwiftUI color

Jetpack Compose color

The nearest match in each system

Similar colors

Open #0F172A in the tools