Tailwind CSS v3 color

Tailwind indigo-800 #3730A3

Tailwind CSS v3's indigo-800 is #3730A3. It is a dark vivid blue in the blue family. In OKLCH it sits at lightness 0.398, chroma 0.177 and hue 277.4°. The nearest CSS named color is darkslateblue (#483D8B), ΔE2000 6.3 away.

Relative luminance
0.0557
OKLCH L · C · h
0.398 · 0.177 · 277.4
Best text
White 9.93:1
Hue family
Blue
Inspect this color Check contrast

#3730A3 color codes

HEX
#3730A3
RGB
rgb(55, 48, 163)
HSL
hsl(244, 55%, 41%)
OKLCH
oklch(0.398 0.177 277.4)
OKLab
oklab(0.398 0.023 -0.176)
CIELAB (D65)
L* 28.30, a* 38.97, b* -60.93
XYZ (D65)
X 9.24, Y 5.57, Z 35.23
CMYK (naive)
cmyk(66%, 71%, 0%, 36%)

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 #3730A3 accessible?

White text on it reaches 9.93:1, passing AAA. Black text fails at 2.11:1.

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

    2.11:1

    • AA fails
    • AA large fails
    • AAA fails
    • APCA Lc +11

  • White text on it

    9.93:1

    • AA passes
    • AA large passes
    • AAA passes
    • APCA Lc −96

  • As text on black

    2.11:1

    • AA fails
    • AA large fails
    • AAA fails
    • APCA Lc −10

  • As text on white

    9.93:1

    • AA passes
    • AA large passes
    • AAA passes
    • APCA Lc +92

Nearest versions that pass 4.5:1

  • For text on white

    #3730A3 9.93:1

    It already reaches 9.93:1 on white, so no change is needed.

  • For text on black

    #6267DE 4.51:1

    Lightening its OKLCH lightness from 0.40 to 0.57 reaches 4.51:1 on black, keeping the hue.

    Compare both in the Contrast System

Checking another pair? Use the Contrast Checker.

Studio

Adjust #3730A3 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 #3730A3

Eleven OKLCH lightness steps at this hue, each with its contrast against white and black. #3730A3 sits at step 800.

  1. 50#F2F4FF
    White
    1.09
    Black
    19.15
  2. 100#E6EAFF
    White
    1.19
    Black
    17.57
  3. 200#CDD5FF
    White
    1.44
    Black
    14.55
  4. 300#ADB8FF
    White
    1.89
    Black
    11.07
  5. 400#8B96FF
    White
    2.65
    Black
    7.90
  6. 500#6F76EE
    White
    3.81
    Black
    5.50
  7. 600#595DD2
    White
    5.35
    Black
    3.92
  8. 700#4545B5
    White
    7.57
    Black
    2.77
  9. 800This color#3730A3
    White
    9.93
    Black
    2.11
  10. 900#1F116F
    White
    15.35
    Black
    1.36
  11. 950#10004C
    White
    18.64
    Black
    1.12

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

Tailwind CSS v3 indigo scale

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

  1. 50#EEF2FF
    White
    1.11
    Black
    18.78
  2. 100#E0E7FF
    White
    1.23
    Black
    17.04
  3. 200#C7D2FE
    White
    1.49
    Black
    14.07
  4. 300#A5B4FC
    White
    1.99
    Black
    10.53
  5. 400#818CF8
    White
    2.98
    Black
    7.04
  6. 500#6366F1
    White
    4.46
    Black
    4.70
  7. 600#4F46E5
    White
    6.28
    Black
    3.33
  8. 700#4338CA
    White
    7.90
    Black
    2.65
  9. 800This color#3730A3
    White
    9.93
    Black
    2.11
  10. 900#312E81
    White
    11.42
    Black
    1.83
  11. 950#1E1B4B
    White
    15.98
    Black
    1.31

Gamut

How vivid #3730A3 can get

At its lightness and hue, sRGB reaches OKLCH chroma 0.246; #3730A3 uses 72% of it. Display P3 reaches no further at this hue.

0.00.20.40.60.80.20.40.60.8 460480500520540560580600620
  • sRGB
  • Display P3
  • Rec. 2020
  • Dominant wavelength
OKLCH chroma
0.177
sRGB edge
0.246
Display P3 edge
0.249
Rec. 2020 edge
0.267
Dominant wavelength
463 nm
Excitation purity
74%
Chromaticity
x 0.1847, y 0.1113
  • This color#3730A3
  • Most vivid in sRGB#3900C6
  • Most vivid in Display P3oklch(0.398 0.249 277.4)

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

Use the wider color where screens show it
.accent {
  color: #3730a3;
}
@media (color-gamut: p3) {
  .accent { color: color(display-p3 0.2027 0 0.7499); }
}

Mixing

Mixing #3730A3

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%#9B98D1
  • OKLab50%#9099D5
  • OKLCH50%#9099D5

Black #000000

  • sRGB50%#1C1852
  • OKLab50%#0F0C3C
  • OKLCH50%#0F0C3C

Its complement #544700

  • sRGB50%#463C52
  • OKLab50%#414561
  • OKLCH50%#7D1E3B
In CSS
/* A gradient and a mix, worked out in OKLCH */
background: linear-gradient(in oklch, #3730a3, white);
color: color-mix(in oklch, #3730a3 50%, white);

In use

#3730A3 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, 4.5:19.93:1 Passes
  • Link and body-size textText, 4.5:19.93:1 Passes
  • Large headingLarge text, 3:19.93:1 Passes
  • Icons, borders and focus ringsNon-text, 3:19.93:1 Passes

Dark page

  • Button labelText, 4.5:19.93:1 Passes
  • Link and body-size textText, 4.5:11.88:1 Fails
  • Large headingLarge text, 3:11.88:1 Fails
  • Icons, borders and focus ringsNon-text, 3:11.88:1 Fails

For text on this page, the nearest shade that passes is #6A71E8 4.58:1

Color vision

How #3730A3 looks with color blindness

Achromatopsia changes it most, ΔE2000 27.6; deuteranopia changes it least, 7.3.

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

    #0048A6 ΔE2000 10.1

    Distinct

    Reads as dark soft blue

  • Deuteranopia

    No working green (medium-wavelength) cones

    #003EA1 ΔE2000 7.3

    Noticeable

    Reads as dark vivid blue

  • Tritanopia

    No working blue (short-wavelength) cones

    #004F66 ΔE2000 17.6

    Distinct

    Reads as dark muted blue

  • Achromatopsia

    No cone color vision; lightness only

    #434343 ΔE2000 27.6

    Distinct

    Reads as dark gray

Pairing check

Checked against its complement, #544700. Their lightness contrast is only 1.07:1, so where hue collapses, add a label, icon or pattern.

VisionThe pairΔE2000Verdict
Normal vision#3730A3 · #54470056.9Stays distinct
Protanopia#0048A6 · #50450052.6Stays distinct
Deuteranopia#003EA1 · #53490554.0Stays distinct
Tritanopia#004F66 · #5C403B34.2Stays distinct
Achromatopsia#434343 · #4848481.7Easily confused

Harmony

Color harmonies for #3730A3

Its complement is #544700, a dark muted 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#3730A3
  • Complement#544700

Complementary

Open in Harmony Studio
  • −30°#004A7D
  • Base#3730A3
  • +30°#611B8F

Analogous

Open in Harmony Studio
  • Base#3730A3
  • +120°#7F2200
  • +240°#005632

Triadic

Open in Harmony Studio
  • Base#3730A3
  • +150°#663C00
  • +210°#385100

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-indigo-800: #3730a3;
}

Tailwind config

// tailwind.config.js — already built in as indigo-800;
// pin the v3 value explicitly like this:
module.exports = {
  theme: {
    extend: {
      colors: {
        indigo: { 800: '#3730a3' },
      },
    },
  },
};

Tailwind v4 theme

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

@theme {
  /* v4 has its own indigo-800; this pins the v3 value. */
  --color-indigo-800: oklch(0.398 0.177 277.4);
}

Design token (W3C DTCG)

{
  "color": {
    "indigo-800": {
      "$type": "color",
      "$value": {
        "colorSpace": "srgb",
        "components": [0.2157, 0.1882, 0.6392],
        "hex": "#3730a3"
      },
      "$description": "Tailwind CSS v3 indigo-800"
    }
  }
}

SwiftUI color

import SwiftUI

enum Palette {
    static let indigo800 = Color(.sRGB, red: 0.216, green: 0.188, blue: 0.639, opacity: 1)
}

Jetpack Compose color

import androidx.compose.ui.graphics.Color

object Palette {
    val Indigo800 = Color(0xFF3730A3)
}

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.

Neighbors

The eight nearest colors on this site by ΔE2000, closest first. Under 2 is hard to tell apart side by side.

Tools

Open #3730A3 in the tools

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