jmagly Color Accessibility Skill
Purpose
Analyze color palettes for WCAG 2.1 accessibility compliance. Calculate contrast ratios for all color pairs, identify failing combinations, and suggest fixes to meet AA or AAA standards.
When This Skill Applies
- User asks "are these colors accessible?"
- User wants to "check contrast ratios"
- User needs "WCAG compliance" for a palette
- User asks about "color accessibility"
- User wants to ensure colors work for colorblind users
- User mentions "AA" or "AAA" standards
Trigger Phrases
| Natural Language | Action |
|---|---|
| "Check if these colors are accessible" | Full WCAG analysis |
| "What's the contrast ratio?" | Calculate specific pair ratio |
| "Make this palette AA compliant" | Analyze + suggest fixes |
| "Is this readable?" | Text contrast check |
| "Color blind friendly?" | Color vision deficiency check |
| "Fix the accessibility of this palette" | Remediation suggestions |
Parameters
--palette <colors>— Comma-separated color values to analyze--foreground <color>— Specific foreground color (for pair check)--background <color>— Specific background color (for pair check)--standard <level>— Target standard: A, AA (default), AAA--fix— Include remediation suggestions for failing pairs--matrix— Show full contrast matrix for all pairs
Analysis Process
1. Parse Colors
Accept colors in any format and normalize to HEX + RGB + HSL:
- HEX:
#1a1a2e,#fff - RGB:
rgb(26, 26, 46) - HSL:
hsl(240, 28%, 14%) - Named:
navy,coral,forestgreen
2. Calculate Relative Luminance
For each color, calculate relative luminance per WCAG 2.1:
For each channel (R, G, B):
sRGB = channel / 255
linear = sRGB <= 0.04045
? sRGB / 12.92
: ((sRGB + 0.055) / 1.055) ^ 2.4
L = 0.2126 * R_linear + 0.7152 * G_linear + 0.0722 * B_linear
3. Calculate Contrast Ratios
For every foreground/background pair:
ratio = (max(L1, L2) + 0.05) / (min(L1, L2) + 0.05)
4. Evaluate Against Standards
| Standard | Normal Text (< 18pt) | Large Text (>= 18pt or 14pt bold) | UI Components |
|---|---|---|---|
| A | No minimum | No minimum | No minimum |
| AA | 4.5:1 | 3:1 | 3:1 |
| AAA | 7:1 | 4.5:1 | 4.5:1 |
5. Generate Contrast Matrix
For N colors, generate an N x N matrix:
Contrast Matrix (AA Standard)
#1a1a2e #16213e #0f3460 #e94560 #ffffff
#1a1a2e — 1.2:1 1.8:1 5.4:1 14.2:1
FAIL FAIL PASS PASS
#16213e 1.2:1 — 1.5:1 4.5:1 11.8:1
FAIL FAIL PASS PASS
#0f3460 1.8:1 1.5:1 — 3.0:1 7.9:1
FAIL FAIL FAIL PASS
#e94560 5.4:1 4.5:1 3.0:1 — 2.6:1
PASS PASS FAIL FAIL
#ffffff 14.2:1 11.8:1 7.9:1 2.6:1 —
PASS PASS PASS FAIL
6. Color Vision Deficiency Check
Simulate how the palette appears under common color vision deficiencies:
| Type | Prevalence | Affected Colors |
|---|---|---|
| Protanopia (no red) | ~1% males | Red-green confusion |
| Deuteranopia (no green) | ~1% males | Red-green confusion |
| Tritanopia (no blue) | ~0.003% | Blue-yellow confusion |
| Achromatopsia (no color) | ~0.003% | All hues lost |
Check that colors remain distinguishable under each simulation. Flag pairs that become indistinguishable.
7. Remediation Suggestions
When --fix is specified, for each failing pair suggest adjustments:
- Darken the darker color or lighten the lighter color
- Adjust saturation to increase perceived contrast
- Suggest the minimum lightness shift needed to pass
- Provide the adjusted color value
Failing pair: #0f3460 on #e94560 (3.0:1, needs 4.5:1)
Suggestions:
Option A: Darken background → #0a2340 (ratio: 4.6:1) PASS
Option B: Lighten foreground → #ff6b7f (ratio: 4.5:1) PASS
Option C: Use white text instead → #ffffff on #e94560 (2.6:1) FAIL
Use white on darkened → #ffffff on #c93050 (4.8:1) PASS
Output Format
Summary View (default)
Accessibility Report — AA Standard
Palette: #1a1a2e, #16213e, #0f3460, #e94560, #ffffff
Overall: 6/10 pairs pass AA (60%)
PASSING (6):
#1a1a2e on #e94560 — 5.4:1 (AA normal text)
#1a1a2e on #ffffff — 14.2:1 (AAA normal + large)
#16213e on #e94560 — 4.5:1 (AA normal text, borderline)
#16213e on #ffffff — 11.8:1 (AAA normal + large)
#0f3460 on #ffffff — 7.9:1 (AAA normal + large)
#e94560 on #1a1a2e — 5.4:1 (AA normal text)
FAILING (4):
#1a1a2e on #16213e — 1.2:1 (needs 4.5:1)
#1a1a2e on #0f3460 — 1.8:1 (needs 4.5:1)
#16213e on #0f3460 — 1.5:1 (needs 4.5:1)
#e94560 on #ffffff — 2.6:1 (needs 4.5:1)
Recommendations:
- Avoid using dark colors on each other for text
- #e94560 needs a darker variant for use on white backgrounds
- Consider adding a dark text color (#1a1a2e) for light backgrounds
Pair Check View
Contrast Check
Foreground: #e94560 (Coral Red)
Background: #1a1a2e (Dark Navy)
Contrast Ratio: 5.4:1
AA Normal Text (4.5:1): PASS
AA Large Text (3.0:1): PASS
AAA Normal Text (7.0:1): FAIL (need 7.0:1)
AAA Large Text (4.5:1): PASS
Best Practices
- Test text on backgrounds, not just swatches — A palette can look cohesive but fail for readability
- Check both directions — Light text on dark AND dark text on light
- Include white and near-black — Most palettes need a light and dark neutral for text
- Don't rely on color alone — Use icons, patterns, or labels alongside color for meaning
- Test at actual sizes — Large text thresholds are different from normal text
- Consider dark mode — Recalculate for dark mode backgrounds