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blue · cool

#3678df

a balanced, vivid blue · cool · closest name: Steel Blue

Token name suggestion: Atlas Harbour

RGB
54, 120, 223
HSL
217°, 73%, 54%
CMYK
76, 46, 0, 13
Luminance
0.1954

#3678df is a balanced vivid blue, 217° on the wheel and 96/100 on the cool side. Put black text on it (4.91:1). As text it scores 4.28:1 on white — large text only. Nearest name is Steel Blue, nearest Tailwind family is blue.

hsl(217 73% 54%)rgb(54 120 223)Base step 500AA inkCool

At a glance

Every number on this page in one read: what #3678df is made of, how bright it looks, and which way it leans.

Hex
#3678df
Hue
217°
blue
Saturation
73%
vivid
Lightness
54%
balanced
Brightness
87%
HSV value
Perceived
48%
weighted brightness
Luminance
0.1954
WCAG relative
Temperature
Cool
96/100 cool
Color family
Blue
Tone
Vivid
Best ink
Black
4.91:1
Closest name
Steel Blue
ΔE2000 6.1
Chroma
60.4
LCH, 0–130ish
OKLCH L
0.585
perceptual lightness
Tailwind
blue
500 · ΔE 4.3
Web-safe
#3366CC
nearest of 216
Where it sits
Hue217° of 360°
Saturation73%
Lightness54%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #3678df.

Temperature
Warm ← → Cool96% cool

Reads cool. Warm and cool siblings keep the same lightness, so you can swap one in without redoing your contrast maths.

Luminance by channel
Red4%
Green69%
Blue27%

Green carries most of what the eye calls brightness — that is why WCAG weights it 0.7152.

Every format

HEX#3678df
HEX (8-digit)#3678dfff
RGBrgb(54, 120, 223)
RGBArgba(54, 120, 223, 1)
HSLhsl(217, 73%, 54%)
HSV / HSBhsv(217, 76%, 87%)
HWBhwb(217 21% 13%)
CMYKcmyk(76%, 46%, 0%, 13%)
LABlab(51.3 14.7 -58.5)
LCHlch(51.3 60.4 284.1)
OKLCHoklch(0.585 0.171 259.2)
XYZ (D65)xyz(21.55, 19.54, 72.43)
Decimal3569887
Display P3color(display-p3 0.212 0.471 0.875)
Web-safe#3366CC

Copy-ready code

every platformclick to select
/* CSS */
color: #3678df;
background-color: #3678df;
/* CSS custom property */
--brand: #3678df;
/* Tailwind (arbitrary) */
class="text-[#3678df] bg-[#3678df]"
/* SCSS */
$brand: #3678df;
/* SwiftUI */
Color(red: 0.212, green: 0.471, blue: 0.875)
/* UIKit */
UIColor(red: 0.212, green: 0.471, blue: 0.875, alpha: 1)
/* Android XML */
<color name="brand">#3678DF</color>
/* Android Compose */
Color(0xFF3678DF)
/* Flutter */
Color(0xFF3678DF)
/* Python / OpenCV (BGR) */
(223, 120, 54)
/* Python / PIL (RGB) */
(54, 120, 223)
/* Java AWT */
new Color(54, 120, 223)
/* .NET */
Color.FromArgb(255, 54, 120, 223)
/* OpenGL / Unity (0–1) */
(0.2118f, 0.4706f, 0.8745f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{54,120,223}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #3678df 85%, white);
border-color: color-mix(in oklab, #3678df 40%, transparent);
/* theme-aware in one line */
color: light-dark(#12366E, #D3DDEE);
/* relative colour syntax */
--hover: hsl(from #3678df h s calc(l - 7));

Design tokens

The same ramp in the four formats a team actually needs. Paste one and the whole palette lands with it.

css custom propertiesclick to select
:root {
  --brand-50: #F3F6FC;
  --brand-100: #E7EEF8;
  --brand-200: #C9D9F3;
  --brand-300: #9EBEF0;
  --brand-400: #6E9DE8;
  --brand-500: #3678df;
  --brand-600: #2267D3;
  --brand-700: #1C56B0;
  --brand-800: #16458D;
  --brand-900: #143466;
  --brand-950: #0D2140;
  --brand: #3678df;
  --brand-ink: #000000;
  --brand-surface: #F4F7FA;
  --brand-border: #C0D1ED;
  --brand-hover: #2165D0;
  --brand-pressed: #1C56B1;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141A24;
    --brand-ink: #D3DDEE;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F3F6FC',
        100: '#E7EEF8',
        200: '#C9D9F3',
        300: '#9EBEF0',
        400: '#6E9DE8',
        500: '#3678df',
        600: '#2267D3',
        700: '#1C56B0',
        800: '#16458D',
        900: '#143466',
        950: '#0D2140',
        DEFAULT: '#3678df',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F3F6FC,
  '100': #E7EEF8,
  '200': #C9D9F3,
  '300': #9EBEF0,
  '400': #6E9DE8,
  '500': #3678df,
  '600': #2267D3,
  '700': #1C56B0,
  '800': #16458D,
  '900': #143466,
  '950': #0D2140,
);
$brand-base: #3678df;
$brand-ink: #000000;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F3F6FC", "$type": "color" },
      "100": { "$value": "#E7EEF8", "$type": "color" },
      "200": { "$value": "#C9D9F3", "$type": "color" },
      "300": { "$value": "#9EBEF0", "$type": "color" },
      "400": { "$value": "#6E9DE8", "$type": "color" },
      "500": { "$value": "#3678df", "$type": "color" },
      "600": { "$value": "#2267D3", "$type": "color" },
      "700": { "$value": "#1C56B0", "$type": "color" },
      "800": { "$value": "#16458D", "$type": "color" },
      "900": { "$value": "#143466", "$type": "color" },
      "950": { "$value": "#0D2140", "$type": "color" }
    },
    "brandInk": { "$value": "#000000", "$type": "color" }
  }
}

Best text color

Only one of black and white can be right. This is the one, with the number that proves it.

Readable at a glance#000000 on #3678df · 4.91:1
Use #000000AA at every size, AAA for large text only.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 4.28:1
AA fail · AA large pass · AAA fail
Aa
Black text · 4.91:1 · recommended
AA pass · AA large pass · AAA fail
Reading the other direction: #3678df as text scores 4.28:1 on white and 4.91:1 on black.
Best tinted ink on it, if plain black or white feels flat: #12366E at 2.76:1.

Make it accessible

A contrast checker tells you that you failed. This tells you what to ship instead — same hue, same saturation, lightness moved only as far as WCAG demands.

The quick fox
#2D72DE · 4.59:1
AA on white−2% L
#2D72DE
The quick fox
#1C54AD · 7.19:1
AAA on white−15% L
#1C54AD
The quick fox
#3678df · 4.91:1
AA on blackalready passes
#3678df
The quick fox
#6698E7 · 7.21:1
AAA on black+11% L
#6698E7

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #3678DF is enough for headings on white. Non-text elements such as icons, chart strokes and focus rings also sit at 3:1 under WCAG 2.2 (1.4.11).

Accessibility — WCAG contrast

Aa
#3678df on white: 4.28:1
AA ✗ fail · AA-large · AAA
Aa
#3678df on black: 4.91:1
AA ✓ pass · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #3678df as text on that neutral, and that neutral as text on #3678df.

NeutralRatioBoth directions
White4.28:1AaAa
Slate 504.09:1AaAa
Slate 1003.90:1AaAa
Slate 2003.47:1AaAa
Slate 3002.88:1AaAa
Slate 4001.67:1AaAa
Slate 5001.11:1AaAa
Slate 6001.77:1AaAa
Slate 7002.42:1AaAa
Slate 8003.42:1AaAa
Slate 9004.17:1AaAa
Black4.91:1AaAa
Colour vision deficiency
true color
protanopia · #4183E3
deuteranopia · #1473DD
tritanopia · #0090A1

Roughly one man in twelve has some form of colour vision deficiency. If any of the three panels above is hard to tell apart from a neighbouring colour in your palette, add a shape, an icon or a label so the meaning does not rest on hue alone.

Color scale — 50 to 950

A Tailwind-shaped ramp built around this exact hex. #3678df is pinned to step 500; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F3F6FC
#E7EEF8
#C9D9F3
#9EBEF0
#6E9DE8
#3678df
#2267D3
#1C56B0
#16458D
#143466
#0D2140
Base = 500Lightest = 50 · #F3F6FCDarkest = 950 · #0D2140Text step on white = 600
Perceptual ramp — OKLCH

The same eleven steps expressed in OKLCH, where equal lightness numbers actually look equally spaced. HSL ramps go muddy in the yellows and washed out in the blues; this one does not. Modern browsers render it natively — the hex ramp above is the fallback.

50100200300400500600700800900950
oklch tokensclick to select
:root {
  --brand-50: oklch(0.97 0.043 259.2);
  --brand-100: oklch(0.94 0.068 259.2);
  --brand-200: oklch(0.88 0.103 259.2);
  --brand-300: oklch(0.80 0.133 259.2);
  --brand-400: oklch(0.72 0.157 259.2);
  --brand-500: oklch(0.64 0.171 259.2);
  --brand-600: oklch(0.56 0.171 259.2);
  --brand-700: oklch(0.48 0.161 259.2);
  --brand-800: oklch(0.40 0.144 259.2);
  --brand-900: oklch(0.32 0.120 259.2);
  --brand-950: oklch(0.24 0.094 259.2);
}

Colors that work with #3678df

Not a palette — a role sheet. Each swatch answers one question you will hit while building the component.

Text on it#000000
Black wins here
Surface#F4F7FA
Tinted page background
Border#C0D1ED
Hairlines and dividers
Muted text#4B6A9B
Captions on the surface
Accent#B45118
Second voice, not a rival
Dark variant#12366E
Hover, pressed, headers
Light variant#E9F0FB
Selected rows, tints
Dark surface#141A24
Dark-mode background
Hover#2165D0
One step down in lightness
Pressed#1C56B1
Two steps down
Disabled#B5C0D0
Chroma pulled out
Focus ring#3D81EC
Offset from the fill so it reads
Light mode
Everything in its place

Surface, border, heading and body all derive from this one hue, so the screen stays coherent without a second palette.

Primary actionSecondaryBadge
Dark mode
Same hue, inverted

Lightness flips, hue holds. The accent stays the anchor in both themes.

Primary actionSecondaryAccent

In real components

The same eight roles, wired into the interface patterns you will actually build with them. Every state below is a computed value, not a mock-up.

Buttons and states
Save changesHoverPressedDisabled
OutlineSubtleLinkFocused
Form field
you@company.com

Focus ring uses the light variant so the field still reads as one shape.

Send me product updates
Notice
Your export is ready

The file stays available for seven days. Download it before it expires.

NewBetaDraft
Data
Storage used68%
Acme LtdActive
NorthwindTrial
GlobexActive

How to use #3678df

Derived from its contrast, chroma and lightness — not from taste.

Works well for
  • Headings from 24px up on white
  • Text and icons on dark surfaces
  • Primary buttons and calls to action
  • Focus rings, active and selected states
  • Brand accents, badges and data highlights
  • Chart series and data categories
Use with care
  • Small text on white — under 4.5:1
  • Full-page backgrounds — tiring over long sessions
  • Pairing with a same-lightness hue — edges vibrate
Minimum size as text on white
24px / 18.66px bold
Safe as a fill behind white type
No — use #12366E
Safe as a 1px border on white
Yes

Meaning and mood

What a colour in this family tends to signal, and how this particular chroma and lightness change the reading.

trustedcalmcompetentcorporate

The default of institutions for a reason: blue is read as stable and safe across nearly every culture that has been surveyed.

This is a confident chroma: strong enough to lead a brand, restrained enough to live in an interface all day. The mid lightness keeps it versatile in both themes.

Worth knowing

It is also the most crowded hue on the web. Distinctiveness has to come from your other choices.

Reads as
  • FormalityMedium
  • EnergyMedium-high
  • Weight46/100
  • TemperatureCool
  • ApproachabilityReserved

Colour associations are cultural and vary by market. Treat these as a starting point for a conversation with your audience, not a finding about them.

Similar colors

One move away from this hex in each direction. Every swatch is its own page.

Color relationships

The wheel positions with their names attached, so you can grab the one you actually need.

Complementary#DF9D36
Analogous left#36CCDF
Analogous right#4936DF
Split-complement 1#DF4936
Split-complement 2#CCDF36
Triadic 1#DF3678
Triadic 2#78DF36
Tetradic#DF36CC
On the wheel
Base+30°−30°+120°+240°+180°217°

#3678df sits at 217°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red21.2%
Green47.1%
Blue87.5%
R · 0–255
54
0x36
G · 0–255
120
0x78
B · 0–255
223
0xdf

CMYK percentages

Cyan75.8%
Magenta46.2%
Yellow0.0%
Key (black)12.5%

Total ink coverage is 135%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#3678df text on a black background

contrast 4.91:1

Card sample

#3678df text on a white background

contrast 4.28:1

Card sample

#3678df on grey

3.90:1

#3678df on its own surface

3.98:1

#3678df on its dark surface

4.08:1

CSS3 live lab

Text font color

The quick brown fox

color: #3678df;
Background color
Panel with #3678df background
background-color: #3678df;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #3678df;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(54, 120, 223, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(54, 120, 223, 0.45);
Border & gradient
Gradient panel
border: 3px solid #3678df;
background: linear-gradient(135deg, #3678df, #6536DF);
Gradient text

Gradient headline

background: linear-gradient(90deg, #3678df, #8F36DF);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #3678df;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #3678df;
caret-color: #3678df;
Left rule
Pull quote or callout
border-left: 4px solid #3678df;
Ring + tint
Selected chip
background: #E9F0FB;
box-shadow: inset 0 0 0 2px #3678df;
Conic badge
68%
background: conic-gradient(#3678df 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #3678df over white; the bottom row is the same alpha over a checkerboard, so you can see what survives on a photo or a video.

Bottom row of hexes is the flattened result over white — use those when a design tool refuses transparency, or when you need a solid fallback.

alpha in every syntaxclick to select
rgba(54, 120, 223, 0.5)
rgb(54 120 223 / 50%)
#3678df80
hsl(217 73% 54% / 50%)
color-mix(in srgb, #3678df 50%, transparent)
Alpha8-digit hexFlat on white
10%#3678df1a#EBF2FC
20%#3678df33#D7E4F9
40%#3678df66#AFC9F2
60%#3678df99#86AEEC
80%#3678dfcc#5E93E5

Gradients from #3678df

Six recipes, each built from this hex and shown with the exact CSS that produced it.

Elevation
Same hue, three lightnesses — safe anywhere
background: linear-gradient(135deg, #6B9BE7, #3678df 45%, #12366E);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #3678df, #6222D4);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #3678df, #DF9D36);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #85ADEC 0%, #3678df 45%, #12366E 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F4F7FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #62E2E6 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #6D50E3 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #12366E 0%, transparent 65%), #3678df;

Monochromatic scale

Palettes built from #3678df

Shades — darker

Tints — lighter

Tones — desaturated

Color harmonies

Nearest named colors

Ranked with CIEDE2000 across all 139 CSS keywords. Under ΔE 2 the eye stops telling them apart; over ΔE 10 they are plainly different colors.

#3678df in the real world

Where a color in this family tends to land, and the interface roles it is usually asked to play.

Industries
TechnologyFinanceHealthcareEnterprise SaaS
Common UI roles
ButtonsLinksFocus statesCharts
Print note

Converts to four-color process without much drama. Proof it anyway.

On screens

Holds up across typical panel gamma. Still worth checking on an uncalibrated laptop, where mid-tones shift most.

In dark mode

Usable as-is on a dark surface at 4.91:1.

Explore nearby colors

Small, deliberate steps away from this hex — useful when you are hunting for the version of a colour that finally feels right.

#3678df, answered

What color is #3678df?

#3678df is a balanced vivid blue, closest to Steel Blue (ΔE2000 6.1). It sits at 217° on the hue wheel with 73% saturation and 54% lightness, which reads as cool.

What is the RGB value of #3678df?

rgb(54, 120, 223) — 54 red, 120 green and 223 blue out of 255, or 21.2% / 47.1% / 87.5% by channel.

What is #3678df in HSL and HSV?

hsl(217, 73%, 54%) and hsv(217, 76%, 87%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #3678df a light or a dark color?

It is a mid-tone. Relative luminance is 0.1954 and perceived brightness is 48%, so black text on it reaches 4.91:1.

Should I use black or white text on #3678df?

Black. It scores 4.91:1 against #3678df, versus 4.28:1 for white — AA at any size.

Is #3678df accessible on a white background?

#3678df on white scores 4.28:1, which only clears AA for large text — 18.66px bold or 24px regular and up. Darken it to #2D72DE to reach 4.5:1, or #1C54AD for 7:1.

What is the complementary color of #3678df?

#DF9D36 sits directly opposite on the wheel. Softer options are the split-complements #DF4936 and #CCDF36, which give the same contrast with far less vibration.

What colors go well with #3678df?

For interface work: #F4F7FA as the surface, #C0D1ED for borders, #4B6A9B for secondary text, #B45118 as an accent and #12366E for hover and pressed states. For a palette, the analogous pair #36CCDF and #4936DF stays calm, while #DF9D36 is the loudest partner.

What is #3678df in CMYK for printing?

cmyk(76%, 46%, 0%, 13%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #3678df warm or cool?

Cool — it scores 96 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #363ADF; nudged cooler, #2071DB.

Which Tailwind color is closest to #3678df?

The blue family — its 500 step is #3b82f6, ΔE2000 4.3 away. That is a visible difference, so define #3678df as a custom token rather than reaching for the built-in.

How do I use #3678df in Tailwind CSS?

Inline it as an arbitrary value with bg-[#3678df] or text-[#3678df], or register the whole ramp under theme.extend.colors.brand so you get bg-brand-500 and friends. The generated 50–950 scale on this page is ready to paste into your config.

What is #3678df with 50% opacity?

rgba(54, 120, 223, 0.5), or #3678df80 in eight-digit hex. Over white that composites to #9BBCEF; over black, #1B3C70.

Is #3678df a web-safe color?

No. The nearest web-safe colour is #3366CC, ΔE2000 6.9 away. The palette only matters for legacy displays and some email clients now.

What does the color #3678df mean?

As a blue, it reads trusted, calm, competent. The default of institutions for a reason: blue is read as stable and safe across nearly every culture that has been surveyed. At this chroma the effect is amplified — it will dominate whatever sits beside it.

What gradient works with #3678df?

The safest is same-hue elevation: linear-gradient(135deg, #6B9BE7, #3678df 45%, #12366E). For more colour, a short hue run to #6222D4 keeps it rich without turning muddy.

Work with #3678df in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #3678df at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.