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cyan · cool

#345666

a dark, soft cyan · cool · closest name: Dark Slate Gray

Token name suggestion: Forest Reef

RGB
52, 86, 102
HSL
199°, 33%, 30%
CMYK
49, 16, 0, 60
Luminance
0.0834

#345666 is a dark soft cyan, 199° on the wheel and 92/100 on the cool side. Put white text on it (7.87:1). As text it scores 7.87:1 on white — safe at any size. Nearest name is Dark Slate Gray, nearest Tailwind family is slate.

hsl(199 33% 30%)rgb(52 86 102)Base step 800AAA inkCool

At a glance

Every number on this page in one read: what #345666 is made of, how bright it looks, and which way it leans.

Hex
#345666
Hue
199°
cyan
Saturation
33%
soft
Lightness
30%
dark
Brightness
40%
HSV value
Perceived
31%
weighted brightness
Luminance
0.0834
WCAG relative
Temperature
Cool
92/100 cool
Color family
Cyan
Tone
Soft
Best ink
White
7.87:1
Closest name
Dark Slate Gray
ΔE2000 8.9
Chroma
15.1
LCH, 0–130ish
OKLCH L
0.434
perceptual lightness
Tailwind
slate
500 · ΔE 14.5
Web-safe
#336666
nearest of 216
Where it sits
Hue199° of 360°
Saturation33%
Lightness30%
Saturation × lightness field

Left edge is grey, right edge is full chroma; top is white, bottom is black. The dot is #345666.

Temperature
Warm ← → Cool92% 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
Red9%
Green80%
Blue11%

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

Every format

HEX#345666
HEX (8-digit)#345666ff
RGBrgb(52, 86, 102)
RGBArgba(52, 86, 102, 1)
HSLhsl(199, 33%, 30%)
HSV / HSBhsv(199, 49%, 40%)
HWBhwb(199 20% 60%)
CMYKcmyk(49%, 16%, 0%, 60%)
LABlab(34.7 -7.5 -13.1)
LCHlch(34.7 15.1 240.1)
OKLCHoklch(0.434 0.048 229.5)
XYZ (D65)xyz(7.14, 8.34, 13.80)
Decimal3429990
Display P3color(display-p3 0.204 0.337 0.400)
Web-safe#336666

Copy-ready code

every platformclick to select
/* CSS */
color: #345666;
background-color: #345666;
/* CSS custom property */
--brand: #345666;
/* Tailwind (arbitrary) */
class="text-[#345666] bg-[#345666]"
/* SCSS */
$brand: #345666;
/* SwiftUI */
Color(red: 0.204, green: 0.337, blue: 0.400)
/* UIKit */
UIColor(red: 0.204, green: 0.337, blue: 0.400, alpha: 1)
/* Android XML */
<color name="brand">#345666</color>
/* Android Compose */
Color(0xFF345666)
/* Flutter */
Color(0xFF345666)
/* Python / OpenCV (BGR) */
(102, 86, 52)
/* Python / PIL (RGB) */
(52, 86, 102)
/* Java AWT */
new Color(52, 86, 102)
/* .NET */
Color.FromArgb(255, 52, 86, 102)
/* OpenGL / Unity (0–1) */
(0.2039f, 0.3373f, 0.4000f, 1f)
/* LaTeX */
\definecolor{brand}{RGB}{52,86,102}
modern cssclick to select
/* mix without leaving CSS */
background: color-mix(in oklab, #345666 85%, white);
border-color: color-mix(in oklab, #345666 40%, transparent);
/* theme-aware in one line */
color: light-dark(#2B4754, #D6E4EA);
/* relative colour syntax */
--hover: hsl(from #345666 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: #F5F8F9;
  --brand-100: #ECF1F4;
  --brand-200: #D4E1E7;
  --brand-300: #B5CDD9;
  --brand-400: #90B5C6;
  --brand-500: #6A9CB3;
  --brand-600: #5389A2;
  --brand-700: #457287;
  --brand-800: #345666;
  --brand-900: #2B444F;
  --brand-950: #1B2A32;
  --brand: #345666;
  --brand-ink: #ffffff;
  --brand-surface: #F5F8FA;
  --brand-border: #C9DBE3;
  --brand-hover: #28424E;
  --brand-pressed: #1C2E37;
}
@media (prefers-color-scheme: dark) {
  :root {
    --brand-surface: #141F24;
    --brand-ink: #D6E4EA;
  }
}
tailwind.config.jsclick to select
theme: {
  extend: {
    colors: {
      brand: {
        50: '#F5F8F9',
        100: '#ECF1F4',
        200: '#D4E1E7',
        300: '#B5CDD9',
        400: '#90B5C6',
        500: '#6A9CB3',
        600: '#5389A2',
        700: '#457287',
        800: '#345666',
        900: '#2B444F',
        950: '#1B2A32',
        DEFAULT: '#345666',
      },
    },
  },
}
scss mapclick to select
$brand: (
  '50': #F5F8F9,
  '100': #ECF1F4,
  '200': #D4E1E7,
  '300': #B5CDD9,
  '400': #90B5C6,
  '500': #6A9CB3,
  '600': #5389A2,
  '700': #457287,
  '800': #345666,
  '900': #2B444F,
  '950': #1B2A32,
);
$brand-base: #345666;
$brand-ink: #ffffff;

@function brand($step) { @return map-get($brand, $step); }
w3c design tokens (json)click to select
{
  "color": {
    "brand": {
      "50": { "$value": "#F5F8F9", "$type": "color" },
      "100": { "$value": "#ECF1F4", "$type": "color" },
      "200": { "$value": "#D4E1E7", "$type": "color" },
      "300": { "$value": "#B5CDD9", "$type": "color" },
      "400": { "$value": "#90B5C6", "$type": "color" },
      "500": { "$value": "#6A9CB3", "$type": "color" },
      "600": { "$value": "#5389A2", "$type": "color" },
      "700": { "$value": "#457287", "$type": "color" },
      "800": { "$value": "#345666", "$type": "color" },
      "900": { "$value": "#2B444F", "$type": "color" },
      "950": { "$value": "#1B2A32", "$type": "color" }
    },
    "brandInk": { "$value": "#ffffff", "$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#ffffff on #345666 · 7.87:1
Use #ffffffAAA at every size.
Aa
12px
Aa
16px
Aa
24px
Aa
White text · 7.87:1 · recommended
AA pass · AA large pass · AAA pass
Aa
Black text · 2.67:1
AA fail · AA large fail · AAA fail
Reading the other direction: #345666 as text scores 7.87:1 on white and 2.67:1 on black.
Best tinted ink on it, if plain black or white feels flat: #EEF4F6 at 7.08:1.

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
#345666 · 7.87:1
AA on whitealready passes
#345666
The quick fox
#345666 · 7.87:1
AAA on whitealready passes
#345666
The quick fox
#4A7B92 · 4.54:1
AA on black+13% L
#4A7B92
The quick fox
#6B9CB4 · 7.04:1
AAA on black+26% L
#6B9CB4

Large text — 24px regular or 18.66px bold and above — only needs 3:1, so #345666 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
#345666 on white: 7.87:1
AA ✓ pass · AA-large · AAA
Aa
#345666 on black: 2.67:1
AA ✗ fail · AA-large · AAA
Against the neutral ladder

Contrast is symmetric, so each row covers both directions: #345666 as text on that neutral, and that neutral as text on #345666.

NeutralRatioBoth directions
White7.87:1AaAa
Slate 507.52:1AaAa
Slate 1007.18:1AaAa
Slate 2006.38:1AaAa
Slate 3005.30:1AaAa
Slate 4003.07:1AaAa
Slate 5001.65:1AaAa
Slate 6001.04:1AaAa
Slate 7001.32:1AaAa
Slate 8001.86:1AaAa
Slate 9002.27:1AaAa
Black2.67:1AaAa
Colour vision deficiency
true color
protanopia · #4E5567
deuteranopia · #474F66
tritanopia · #1D5B5B

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. #345666 is pinned to step 800; the rest hold its hue and let saturation ease off at the extremes so the pale end never turns neon.

#F5F8F9
#ECF1F4
#D4E1E7
#B5CDD9
#90B5C6
#6A9CB3
#5389A2
#457287
#345666
#2B444F
#1B2A32
Base = 800Lightest = 50 · #F5F8F9Darkest = 950 · #1B2A32Text step on white = 700
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 0.012 229.5);
  --brand-100: oklch(0.94 0.019 229.5);
  --brand-200: oklch(0.88 0.028 229.5);
  --brand-300: oklch(0.80 0.037 229.5);
  --brand-400: oklch(0.72 0.044 229.5);
  --brand-500: oklch(0.64 0.048 229.5);
  --brand-600: oklch(0.56 0.048 229.5);
  --brand-700: oklch(0.48 0.045 229.5);
  --brand-800: oklch(0.40 0.040 229.5);
  --brand-900: oklch(0.32 0.033 229.5);
  --brand-950: oklch(0.24 0.026 229.5);
}

Colors that work with #345666

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

Text on it#ffffff
White wins here
Surface#F5F8FA
Tinted page background
Border#C9DBE3
Hairlines and dividers
Muted text#4D8098
Captions on the surface
Accent#693531
Second voice, not a rival
Dark variant#2B4754
Hover, pressed, headers
Light variant#EEF4F6
Selected rows, tints
Dark surface#141F24
Dark-mode background
Hover#28424E
One step down in lightness
Pressed#1C2E37
Two steps down
Disabled#6A8FA0
Chroma pulled out
Focus ring#32657C
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 #345666

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

Works well for
  • Body text and links on white
  • Charts, tags and secondary surfaces
  • Headers, footers and dark-mode surfaces
  • Brand accents, badges and data highlights
Use with care
  • Text on black or near-black surfaces
  • Black text placed on it
  • Thin strokes and 1px borders — they disappear on light UI
  • Pairing with a same-lightness hue — edges vibrate
Minimum size as text on white
Any size
Safe as a fill behind white type
Yes
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.

cleantechnicalfreshclinical

Cyan reads as water, air and infrastructure: cool, hygienic, engineered.

The muted chroma softens the association — it reads considered rather than loud, which suits long-form and data-heavy screens. The low lightness adds weight and formality.

Worth knowing

At high lightness it disappears into white surfaces and thin strokes vanish entirely.

Reads as
  • FormalityHigh
  • EnergyMedium
  • Weight70/100
  • 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#664434
Analogous left#34665D
Analogous right#343D66
Split-complement 1#66343D
Split-complement 2#665D34
Triadic 1#663456
Triadic 2#566634
Tetradic#5D3466
On the wheel
Base+30°−30°+120°+240°+180°199°

#345666 sits at 199°. Every dot is a harmony position and links to its own page in the table alongside.

RGB percentages

Red20.4%
Green33.7%
Blue40.0%
R · 0–255
52
0x34
G · 0–255
86
0x56
B · 0–255
102
0x66

CMYK percentages

Cyan49.0%
Magenta15.7%
Yellow0.0%
Key (black)60.0%

Total ink coverage is 125%. Most commercial presses cap around 300% — above that, sheets stop drying properly.

Color previews

#345666 text on a black background

contrast 2.67:1

Card sample

#345666 text on a white background

contrast 7.87:1

Card sample

#345666 on grey

7.18:1

#345666 on its own surface

7.38:1

#345666 on its dark surface

2.13:1

CSS3 live lab

Text font color

The quick brown fox

color: #345666;
Background color
Panel with #345666 background
background-color: #345666;
Text shadow — hex

Glowing headline

text-shadow: 2px 2px 8px #345666;
Text shadow — RGB

Soft neon halo

text-shadow: 0 0 14px rgba(52, 86, 102, 0.45);
Div box shadow
Elevated card
box-shadow: 0 12px 32px -8px rgba(52, 86, 102, 0.45);
Border & gradient
Gradient panel
border: 3px solid #345666;
background: linear-gradient(135deg, #345666, #343566);
Gradient text

Gradient headline

background: linear-gradient(90deg, #345666, #403466);
-webkit-background-clip: text;
color: transparent;
Focus ring
Focused control
outline: 2px solid #345666;
outline-offset: 3px;
Underline & caret

Marked up text

text-decoration-color: #345666;
caret-color: #345666;
Left rule
Pull quote or callout
border-left: 4px solid #345666;
Ring + tint
Selected chip
background: #EEF4F6;
box-shadow: inset 0 0 0 2px #345666;
Conic badge
68%
background: conic-gradient(#345666 68%, #e2e8f0 0);

Transparency

What each alpha value actually composites to. The top row is #345666 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(52, 86, 102, 0.5)
rgb(52 86 102 / 50%)
#34566680
hsl(199 33% 30% / 50%)
color-mix(in srgb, #345666 50%, transparent)
Alpha8-digit hexFlat on white
10%#3456661a#EBEEF0
20%#34566633#D6DDE0
40%#34566666#AEBBC2
60%#34566699#859AA3
80%#345666cc#5D7885

Gradients from #345666

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, #49788F, #345666 45%, #2B4754);
Duotone
A short hue run reads richer than a flat fill
background: linear-gradient(120deg, #345666, #2C2A52);
Complement sweep
Loud — keep it behind large type only
background: linear-gradient(90deg, #345666, #664434);
Spotlight
Hero panels and app headers
background: radial-gradient(120% 120% at 20% 0%, #5389A3 0%, #345666 45%, #2B4754 100%);
Soft wash
Section backgrounds that stay readable
background: linear-gradient(180deg, #F5F8FA, #ffffff);
Mesh
Ambient background, no image weight
background: radial-gradient(60% 60% at 15% 20%, #458876 0%, transparent 60%), radial-gradient(55% 55% at 85% 15%, #3E447A 0%, transparent 60%), radial-gradient(70% 70% at 50% 95%, #2B4754 0%, transparent 65%), #345666;

Monochromatic scale

Palettes built from #345666

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.

#345666 in the real world

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

Industries
TechnologyTravelHealthcareMedia
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

Too dim on dark surfaces at 2.67:1 — lift it to #4A7B92 for body text, or reserve it for fills.

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.

#345666, answered

What color is #345666?

#345666 is a dark soft cyan, closest to Dark Slate Gray (ΔE2000 8.9). It sits at 199° on the hue wheel with 33% saturation and 30% lightness, which reads as cool.

What is the RGB value of #345666?

rgb(52, 86, 102) — 52 red, 86 green and 102 blue out of 255, or 20.4% / 33.7% / 40% by channel.

What is #345666 in HSL and HSV?

hsl(199, 33%, 30%) and hsv(199, 49%, 40%). HSL is what CSS takes; HSV is what your design tool's picker shows, which is why the saturation numbers rarely match.

Is #345666 a light or a dark color?

It is a dark color. Relative luminance is 0.0834 and perceived brightness is 31%, so white text on it reaches 7.87:1.

Should I use black or white text on #345666?

White. It scores 7.87:1 against #345666, versus 2.67:1 for black — AAA at any size.

Is #345666 accessible on a white background?

#345666 on white scores 7.87:1, which clears AAA at every size.

What is the complementary color of #345666?

#664434 sits directly opposite on the wheel. Softer options are the split-complements #66343D and #665D34, which give the same contrast with far less vibration.

What colors go well with #345666?

For interface work: #F5F8FA as the surface, #C9DBE3 for borders, #4D8098 for secondary text, #693531 as an accent and #2B4754 for hover and pressed states. For a palette, the analogous pair #34665D and #343D66 stays calm, while #664434 is the loudest partner.

What is #345666 in CMYK for printing?

cmyk(49%, 16%, 0%, 60%). This is a screen-to-ink approximation — ask your printer for a proof before committing to a run.

Is #345666 warm or cool?

Cool — it scores 92 on a scale where 0 is the warmest orange and 100 the coolest azure. Nudged warmer it becomes #346664; nudged cooler, #324E68.

Which Tailwind color is closest to #345666?

The slate family — its 500 step is #64748b, ΔE2000 14.5 away. That is a visible difference, so define #345666 as a custom token rather than reaching for the built-in.

How do I use #345666 in Tailwind CSS?

Inline it as an arbitrary value with bg-[#345666] or text-[#345666], 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 #345666 with 50% opacity?

rgba(52, 86, 102, 0.5), or #34566680 in eight-digit hex. Over white that composites to #9AABB3; over black, #1A2B33.

Is #345666 a web-safe color?

No. The nearest web-safe colour is #336666, ΔE2000 11.3 away. The palette only matters for legacy displays and some email clients now.

What does the color #345666 mean?

As a cyan, it reads clean, technical, fresh. Cyan reads as water, air and infrastructure: cool, hygienic, engineered. At this moderate chroma the association is present but not shouted.

What gradient works with #345666?

The safest is same-hue elevation: linear-gradient(135deg, #49788F, #345666 45%, #2B4754). For more colour, a short hue run to #2C2A52 keeps it rich without turning muddy.

Work with #345666 in the Color Lab

Every tool opens with this colour already loaded.

Every value on this page is computed from #345666 at request time — conversions, contrast ratios and ΔE distances are calculated, never looked up.