color-palette

Item: color-palette
Rating: 8.4
Author: Implexa

Generate complete, accessible colour palettes from a single brand hex. Produces 11-shade scale (50-950), semantic tokens, dark mode variants, Tailwind v4 CSS…

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8.4/ 10

evaluated by implexa, claude-haiku-4-5 · 2026-06-19

color-palette generates wcag-compliant 11-shade palettes from a single hex, producing tailwind v4 css with semantic tokens, dark mode variants, and contrast verification. includes working code for conversion and validation.

structure

9.0

trigger phrases

8.0

procedure

9.0

edge cases

8.0

documentation

8.0

strengths

view original SKILL.md from skills.shclick to expand

Colour Palette Generator

Generate a complete, accessible colour system from a single brand hex. Produces Tailwind v4 CSS ready to paste into your project.

Workflow

Step 1: Get the Brand Hex

Ask for the primary brand colour. A single hex like #0D9488 is enough.

Step 2: Generate 11-Shade Scale

Convert hex to HSL, then generate shades by varying lightness while keeping hue constant.

Hex to HSL Conversion
function hexToHSL(hex) {
  hex = hex.replace(/^#/, '');
  const r = parseInt(hex.substring(0, 2), 16) / 255;
  const g = parseInt(hex.substring(2, 4), 16) / 255;
  const b = parseInt(hex.substring(4, 6), 16) / 255;

  const max = Math.max(r, g, b);
  const min = Math.min(r, g, b);
  const diff = max - min;

  let l = (max + min) / 2;
  let s = 0;
  if (diff !== 0) {
    s = l > 0.5 ? diff / (2 - max - min) : diff / (max + min);
  }

  let h = 0;
  if (diff !== 0) {
    if (max === r) h = ((g - b) / diff + (g < b ? 6 : 0)) / 6;
    else if (max === g) h = ((b - r) / diff + 2) / 6;
    else h = ((r - g) / diff + 4) / 6;
  }

  return { h: Math.round(h * 360), s: Math.round(s * 100), l: Math.round(l * 100) };
}

Lightness and Saturation Values

Shade
Lightness
Saturation Mult
Use Case

50
97%
0.80
Subtle backgrounds

100
94%
0.80
Hover states

200
87%
0.85
Borders, dividers

300
75%
0.90
Disabled states

400
62%
0.95
Placeholder text

500
48%
1.00
Brand colour baseline

600
40%
1.00
Primary actions (often the brand colour)

700
33%
1.00
Hover on primary

800
27%
1.00
Active states

900
20%
1.00
Text on light bg

950
10%
1.00
Darkest accents

Reduce saturation for lighter shades (50-200 by 15-20%, 300-400 by 5-10%) to prevent overly vibrant pastels. Keep full saturation for 500-950.

Complete Scale Generator

function generateShadeScale(brandHex) {
  const { h, s } = hexToHSL(brandHex);
  const shades = {
    50:  { l: 97, sMul: 0.8 },  100: { l: 94, sMul: 0.8 },
    200: { l: 87, sMul: 0.85 }, 300: { l: 75, sMul: 0.9 },
    400: { l: 62, sMul: 0.95 }, 500: { l: 48, sMul: 1.0 },
    600: { l: 40, sMul: 1.0 },  700: { l: 33, sMul: 1.0 },
    800: { l: 27, sMul: 1.0 },  900: { l: 20, sMul: 1.0 },
    950: { l: 10, sMul: 1.0 }
  };
  const result = {};
  for (const [shade, { l, sMul }] of Object.entries(shades)) {
    result[shade] = `hsl(${h}, ${Math.round(s * sMul)}%, ${l}%)`;
  }
  return result;
}

HSL to Hex Conversion

function hslToHex(h, s, l) {
  s = s / 100; l = l / 100;
  const c = (1 - Math.abs(2 * l - 1)) * s;
  const x = c * (1 - Math.abs((h / 60) % 2 - 1));
  const m = l - c / 2;
  let r = 0, g = 0, b = 0;
  if (h < 60) { r = c; g = x; }
  else if (h < 120) { r = x; g = c; }
  else if (h < 180) { g = c; b = x; }
  else if (h < 240) { g = x; b = c; }
  else if (h < 300) { r = x; b = c; }
  else { r = c; b = x; }
  r = Math.round((r + m) * 255);
  g = Math.round((g + m) * 255);
  b = Math.round((b + m) * 255);
  return `#${r.toString(16).padStart(2, '0')}${g.toString(16).padStart(2, '0')}${b.toString(16).padStart(2, '0')}`.toUpperCase();
}

Verification

Generated shades should look like the same colour family with smooth progression. Light shades (50-300) usable for backgrounds, dark shades (700-950) usable for text. Brand colour recognisable in 500-700.

Step 3: Map Semantic Tokens

Every background token MUST have a paired foreground token. Never use a background without its pair or dark mode will break.

Light Mode Tokens

Token
Shade
Use Case

background
white
Page backgrounds

foreground
950
Body text

card
white
Card backgrounds

card-foreground
900
Card text

popover
white
Dropdown/tooltip backgrounds

popover-foreground
950
Dropdown text

primary
600
Primary buttons, links

primary-foreground
white
Text on primary buttons

secondary
100
Secondary buttons

secondary-foreground
900
Text on secondary buttons

muted
50
Disabled backgrounds, subtle sections

muted-foreground
600
Muted text, captions

accent
100
Hover states, subtle highlights

accent-foreground
900
Text on accent backgrounds

destructive
red-600
Delete buttons, errors

destructive-foreground
white
Text on destructive buttons

border
200
Input borders, dividers

input
200
Input field borders

ring
600
Focus rings

Dark Mode Tokens

Token
Shade
Use Case

background
950
Page backgrounds

foreground
50
Body text

card
900
Card backgrounds

card-foreground
50
Card text

popover
900
Dropdown backgrounds

popover-foreground
50
Dropdown text

primary
500
Primary buttons (brighter in dark)

primary-foreground
white
Text on primary buttons

secondary
800
Secondary buttons

secondary-foreground
50
Text on secondary buttons

muted
800
Disabled backgrounds

muted-foreground
400
Muted text

accent
800
Hover states

accent-foreground
50
Text on accent backgrounds

destructive
red-500
Delete buttons (brighter)

destructive-foreground
white
Text on destructive

border
800
Borders

input
800
Input borders

ring
500
Focus rings

Dark Mode Inversion Pattern

Dark mode inverts lightness while preserving hue and saturation. Swap extremes (50 becomes 950, 950 becomes 50), preserve middle (500 stays near 500).

Light Shade
Dark Equivalent
Role

50
950
Backgrounds

100
900
Subtle backgrounds

200
800
Borders

500
500 (slightly brighter)
Brand baseline

600
400
Primary actions

950
50
Text colour

Key dark mode principles:

Use shade 500 (not 600) for primary -- brighter for visibility on dark backgrounds

Use shade 50 (off-white) for text instead of pure #FFFFFF -- easier on eyes

Borders need ~10-15% lighter than background (e.g. 800 border on 950 background)

Higher elevation = lighter colour (opposite of light mode shadows)

Always update foreground when changing background

Step 4: Check Contrast

WCAG Minimum Ratios

Content Type
AA
AAA

Normal text (<18px or <14px bold)
4.5:1
7:1

Large text (>=18px or >=14px bold)
3:1
4.5:1

UI components (buttons, borders)
3:1
Not defined

Graphical objects (icons, charts)
3:1
Not defined

Target AA for most projects, AAA for high-accessibility needs (government, healthcare).

Luminance and Contrast Formulas

function getLuminance(hex) {
  hex = hex.replace(/^#/, '');
  const r = parseInt(hex.substring(0, 2), 16) / 255;
  const g = parseInt(hex.substring(2, 4), 16) / 255;
  const b = parseInt(hex.substring(4, 6), 16) / 255;
  const rsRGB = r <= 0.03928 ? r / 12.92 : Math.pow((r + 0.055) / 1.055, 2.4);
  const gsRGB = g <= 0.03928 ? g / 12.92 : Math.pow((g + 0.055) / 1.055, 2.4);
  const bsRGB = b <= 0.03928 ? b / 12.92 : Math.pow((b + 0.055) / 1.055, 2.4);
  return 0.2126 * rsRGB + 0.7152 * gsRGB + 0.0722 * bsRGB;
}

function getContrastRatio(hex1, hex2) {
  const lum1 = getLuminance(hex1);
  const lum2 = getLuminance(hex2);
  const lighter = Math.max(lum1, lum2);
  const darker = Math.min(lum1, lum2);
  return (lighter + 0.05) / (darker + 0.05);
}

Quick Check Table -- Light Mode

Foreground
Background
Ratio
Pass?
Use Case

950
white
18.5:1
AAA
Body text

900
white
14.2:1
AAA
Card text

700
white
8.1:1
AAA
Text

600
white
5.7:1
AA
Text, buttons

500
white
3.9:1
Fail
Too light for text

white
600
5.7:1
AA
Button text

white
700
8.1:1
AAA
Button text

600
50
5.4:1
AA
Muted section text

Quick Check Table -- Dark Mode

Foreground
Background
Ratio
Pass?
Use Case

50
950
18.5:1
AAA
Body text

50
900
14.2:1
AAA
Card text

400
950
8.2:1
AAA
Muted text

400
900
6.3:1
AA
Muted text

white
600
5.7:1
AA
Button text

Rule of thumb: For text, aim for 50%+ lightness difference between foreground and background.

Essential Pairs to Verify

Body text: foreground on background (light: 950 on white = 18.5:1, dark: 50 on 950 = 18.5:1)

Primary button: primary-foreground on primary (light: white on 600 = 5.7:1, dark: white on 500 = 3.9:1 -- borderline)

Muted text: muted-foreground on muted (light: 600 on 50 = 5.4:1, dark: 400 on 800 = 4.1:1 -- may fail)

Card text: card-foreground on card (light: 900 on white = 14.2:1, dark: 50 on 900 = 14.2:1)

Fixing Common Contrast Failures

White on primary-500 fails (3.9:1): Use primary-600 instead (5.7:1), or use dark text on the button.

Muted text in dark mode fails (400 on 800 = 4.1:1): Use 300 on 900 = 6.8:1.

Links hard to see (500 on white = 3.9:1): Use primary-700 (8.1:1), or add underline decoration.

Step 5: Output Tailwind v4 CSS

@import "tailwindcss";

@theme {
  /* Shade scale */
  --color-primary-50: #F0FDFA;
  --color-primary-100: #CCFBF1;
  --color-primary-200: #99F6E4;
  --color-primary-300: #5EEAD4;
  --color-primary-400: #2DD4BF;
  --color-primary-500: #14B8A6;
  --color-primary-600: #0D9488;
  --color-primary-700: #0F766E;
  --color-primary-800: #115E59;
  --color-primary-900: #134E4A;
  --color-primary-950: #042F2E;

  /* Light mode semantic tokens */
  --color-background: #FFFFFF;
  --color-foreground: var(--color-primary-950);
  --color-card: #FFFFFF;
  --color-card-foreground: var(--color-primary-900);
  --color-popover: #FFFFFF;
  --color-popover-foreground: var(--color-primary-950);
  --color-primary: var(--color-primary-600);
  --color-primary-foreground: #FFFFFF;
  --color-secondary: var(--color-primary-100);
  --color-secondary-foreground: var(--color-primary-900);
  --color-muted: var(--color-primary-50);
  --color-muted-foreground: var(--color-primary-600);
  --color-accent: var(--color-primary-100);
  --color-accent-foreground: var(--color-primary-900);
  --color-destructive: #DC2626;
  --color-destructive-foreground: #FFFFFF;
  --color-border: var(--color-primary-200);
  --color-input: var(--color-primary-200);
  --color-ring: var(--color-primary-600);
  --radius: 0.5rem;
}

/* Dark mode overrides */
.dark {
  --color-background: var(--color-primary-950);
  --color-foreground: var(--color-primary-50);
  --color-card: var(--color-primary-900);
  --color-card-foreground: var(--color-primary-50);
  --color-popover: var(--color-primary-900);
  --color-popover-foreground: var(--color-primary-50);
  --color-primary: var(--color-primary-500);
  --color-primary-foreground: #FFFFFF;
  --color-secondary: var(--color-primary-800);
  --color-secondary-foreground: var(--color-primary-50);
  --color-muted: var(--color-primary-800);
  --color-muted-foreground: var(--color-primary-400);
  --color-accent: var(--color-primary-800);
  --color-accent-foreground: var(--color-primary-50);
  --color-destructive: #EF4444;
  --color-destructive-foreground: #FFFFFF;
  --color-border: var(--color-primary-800);
  --color-input: var(--color-primary-800);
  --color-ring: var(--color-primary-500);
}

Copy assets/tailwind-colors.css as a starting template.

Component Usage Examples

// Primary button
<button className="bg-primary text-primary-foreground hover:bg-primary/90">Click me</button>

// Secondary button
<button className="bg-secondary text-secondary-foreground hover:bg-secondary/80">Cancel</button>

// Card
<div className="bg-card text-card-foreground border-border rounded-lg">
  <h2>Title</h2>
  <p className="text-muted-foreground">Description</p>
</div>

// Input
<input className="bg-background text-foreground border-input focus:ring-ring" />

Common Adjustments

Too vibrant at light shades: Reduce saturation by 10-20%

Poor contrast on primary: Use shade 700+ for text

Dark mode too dark: Use shade 900 instead of 950 for backgrounds

Brand colour too light/dark: Adjust to shade 500-600 range

Dark mode looks washed out: Use shade 500 for primary (brighter than light mode's 600)

Pure white text too harsh in dark mode: Use shade 50 (off-white) instead

Dark mode muted text fails contrast: Use more extreme shades (300 on 900 instead of 400 on 800)

Brand Identity Adjustments

Conservative brands (finance, law): Use primary-700 for buttons, reduce saturation in light shades

Vibrant brands (creative, tech): Use primary-500-600, keep full saturation

Minimal brands (design, architecture): Use primary sparingly, emphasise muted tones, subtle borders (primary-100)

Verification Checklist

 Body text: >=4.5:1 (normal) or >=3:1 (large)

 Primary button text: >=4.5:1

 Secondary button text: >=4.5:1

 Muted text: >=4.5:1

 Links: >=4.5:1 (or underlined)

 UI elements (borders): >=3:1

 Focus indicators: >=3:1

 Error text: >=4.5:1

 Dark mode: All above checks pass

 Every background has a foreground pair

 Brand colour recognisable in both modes

 Borders visible but not harsh

 Cards/sections have clear boundaries

Test both modes before shipping.

Optional References

Online contrast checkers: WebAIM (webaim.org/resources/contrastchecker), Coolors (coolors.co/contrast-checker), Accessible Colors (accessible-colors.com)

CI/CD contrast tests: Use getContrastRatio() in test suites to assert minimum ratios for all token pairs

Transparent/gradient edge cases: For colours with opacity, calculate against final rendered colour. For gradients, check both endpoints.

OLED dark mode: Use @media (prefers-contrast: high) with #000000 background for battery savings on AMOLED screens

Multi-colour palettes: Generate separate shade scales for each brand colour, map to different semantic roles (primary, accent)

Palette visualisation tools: coolors.co, paletton.com, Figma swatches

assets/tailwind-colors.css — Complete CSS output template

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intent

generate a production-ready colour system from one brand hex. takes a single colour (#0D9488 style), produces an 11-shade scale with wcag aa/aaa contrast pairs, semantic tokens for light and dark modes, and tailwind v4 css ready to paste into your project. use this when you need a cohesive, accessible colour system fast and don't want to hand-tune every shade.

inputs

brand hex: primary colour in #RRGGBB format (e.g. #0D9488). required. must be valid hex or conversion fails.
contrast target: wcag level (aa or aaa). defaults to aa. aaa tightens the token pairing rules and may reduce usable shades.
dark mode preference: toggle whether to generate dark mode tokens. defaults to on.
saturation adjustment: optional multiplier (0.8 to 1.2) to reduce vibrance at light shades or boost at dark shades. defaults to 1.0 (no adjustment).

procedure

convert brand hex to hsl
- input: brand hex string (e.g. #0D9488)
- extract r, g, b channels as 0-1 range
- calculate max, min, lightness (l) from rgb
- calculate saturation (s) from l and rgb range
- calculate hue (h) from which channel is dominant
- output: object {h: 0-360, s: 0-100, l: 0-100}
generate 11-shade scale by lightness variation
- input: hsl from step 1
- for each shade (50, 100, 200, 300, 400, 500, 600, 700, 800, 900, 950):
  - apply target lightness value (50=97%, 500=48%, 950=10%)
  - apply saturation multiplier (light shades 50-400 get 0.8-0.95x, dark shades 500-950 get 1.0x)
  - keep hue constant
  - output: hsl(h, s%, l%) string for each shade
- convert each hsl back to hex using hue-based rgb calculation
- output: object {50: #..., 100: #..., ..., 950: #...}
map semantic tokens for light mode
- input: 11-shade scale from step 2
- assign shades to semantic roles:
  - background: white, foreground: shade-950
  - card: white, card-foreground: shade-900
  - primary: shade-600, primary-foreground: white
  - secondary: shade-100, secondary-foreground: shade-900
  - muted: shade-50, muted-foreground: shade-600
  - accent: shade-100, accent-foreground: shade-900
  - destructive: #DC2626, destructive-foreground: white
  - border: shade-200
  - input: shade-200
  - ring: shade-600
- output: key-value map of token names to hex colours
map semantic tokens for dark mode (if enabled)
- input: 11-shade scale from step 2
- apply dark mode inversion pattern (swap lightness extremes, preserve middle):
  - background: shade-950, foreground: shade-50
  - card: shade-900, card-foreground: shade-50
  - primary: shade-500 (brighter than light mode 600), primary-foreground: white
  - secondary: shade-800, secondary-foreground: shade-50
  - muted: shade-800, muted-foreground: shade-400
  - accent: shade-800, accent-foreground: shade-50
  - destructive: #EF4444, destructive-foreground: white
  - border: shade-800
  - input: shade-800
  - ring: shade-500
- output: key-value map of dark mode tokens
calculate contrast ratio for each token pair
- input: light mode tokens, dark mode tokens, contrast target (aa or aaa)
- for each foreground-background pair:
  - convert hex to srgb and then to relative luminance (using gamma correction: 0.03928 threshold, 2.4 exponent)
  - calculate wcag contrast ratio: (lighter + 0.05) / (darker + 0.05)
  - compare against target (aa: 4.5:1 for normal text, 3:1 for large text; aaa: 7:1 for normal, 4.5:1 for large)
- output: object {token-pair: {ratio: number, pass: bool, level: 'aa'|'aaa'|'fail'}}
flag contrast failures and suggest fixes
- input: contrast report from step 5
- for each failed pair:
  - if muted-foreground fails: suggest darker shade (e.g. 300 instead of 400)
  - if primary text fails: suggest darker text shade (e.g. 700 instead of 600) or lighter background
  - if secondary fails: swap to darker shade-800 or adjust background
- output: array of {token-pair, current-ratio, target-ratio, suggestion}
build tailwind v4 css output
- input: 11-shade scale (step 2), light mode tokens (step 3), dark mode tokens (step 4), fixes from step 6
- generate @theme block with --color-primary-50 through --color-primary-950 hex variables
- add light mode semantic token variables (--color-background, --color-foreground, etc.)
- add .dark selector with dark mode overrides
- add --radius variable (default 0.5rem)
- output: single css file ready for @import "tailwindcss"; at the top
generate component usage examples
- input: semantic tokens from steps 3 and 4
- write html/jsx snippets showing:
  - primary button with hover state
  - secondary button
  - card with muted text
  - input field with focus ring
- output: code block with 4 examples

decision points

if contrast fails on primary button (white on shade-500): use shade-600 instead (light mode: 5.7:1 vs 3.9:1) or swap to dark text on button. do not ship sub-4.5:1 for wcag aa compliance.
if muted-foreground fails in dark mode (shade-400 on shade-800): use shade-300 on shade-900 (6.8:1 vs 4.1:1). preserve the muted semantic role but adjust shade pairs.
if saturation feels too vibrant at light shades (50-200): apply saturation adjustment (0.8-0.85x). if still too vibrant, reduce to 0.7x. if too muted, increase to 0.9x. this is a visual judgment call, test in ui before shipping.
if dark mode background feels too harsh (shade-950 = 10% lightness): use shade-900 (20% lightness) instead. trade off maximum contrast for readability on oled screens.
if brand colour is unrecognizable in token scale: check that shade-500 or shade-600 still reads as the original brand. if hue shifted or saturation collapsed, rerun step 1 and verify hex conversion. if input hex is already desaturated (low saturation brand), the output will be muted by design.
if token pair has no dark mode equivalent (e.g. destructive uses fixed red, not brand shade): map fixed-colour tokens (destructive, destructive-foreground) separately. do not force brand-shade inversion for semantic roles that must have high contrast (errors, warnings).
if output must support transparent/rgba colours: calculate contrast against the final rendered colour (blend with background), not the rgba value in isolation.
if targeting oled/amoled dark mode with high contrast preference: add @media (prefers-contrast: high) block using #000000 background instead of shade-950 for battery savings and maximum contrast. provide both variants in output.

output contract

output is a single tailwind v4 css file, 150-200 lines, containing:

@import "tailwindcss"; at top
@theme block with --color-primary-50 through --color-primary-950 (11 hex values)
light mode semantic tokens (--color-background, --color-foreground, --color-card, --color-card-foreground, --color-popover, --color-popover-foreground, --color-primary, --color-primary-foreground, --color-secondary, --color-secondary-foreground, --color-muted, --color-muted-foreground, --color-accent, --color-accent-foreground, --color-destructive, --color-destructive-foreground, --color-border, --color-input, --color-ring)
.dark selector with all token overrides (same 18 tokens)
--radius variable (default 0.5rem)

additionally, output a contrast report (json or markdown) listing all token pairs, their ratios, pass/fail status, and wcag level achieved.

file location: save as tailwind-colors.css in project root or src/styles/tailwind-colors.css if following standard structure.

example output structure:

@import "tailwindcss";

@theme {
  --color-primary-50: #F0FDFA;
  --color-primary-100: #CCFBF1;
  /* ... 9 more shades ... */
  --color-primary-950: #042F2E;
  
  --color-background: #FFFFFF;
  --color-foreground: var(--color-primary-950);
  /* ... 17 more light mode tokens ... */
  --radius: 0.5rem;
}

.dark {
  --color-background: var(--color-primary-950);
  --color-foreground: var(--color-primary-50);
  /* ... 17 more dark mode tokens ... */
}

outcome signal

you know this worked when:

css file compiles without errors and can be imported into a tailwind v4 project.
contrast report shows all pairs >= 4.5:1 (wcag aa) or >= 7:1 (wcag aaa), with no "fail" statuses. if any fail, review the fixes column and manually adjust token shades before shipping.
visual test in browser: apply token classes to a card, button, text, and input. light mode should read clearly. switch to dark mode, all elements should remain legible with no washed-out or too-dark text.
brand colour is recognizable in both light and dark modes. shade-500 or shade-600 (light) and shade-500 (dark) should feel like the original brand hex.
borders and dividers are visible but not harsh on backgrounds (typically 3-4 shades lighter or darker, e.g. shade-200 border on white, shade-800 border on shade-950).
paired tokens maintain symmetry: every background token has a foreground counterpart. swapping light and dark should not require manual token remapping.
component examples render without contrast warnings when run through an accessibility checker (axe, lighthouse, etc.).

credits: original skill by jezweb. enriched per implexa standards to add explicit decision logic, edge cases, contrast verification procedure, and dark mode inversion rules.