Contrast Ratio = (L1 + 0.05) / (L2 + 0.05)

Where L1 = lighter color's relative luminance
      L2 = darker color's relative luminance

function relativeLuminance(r, g, b) {
  // Convert 0-255 to 0-1
  let [rs, gs, bs] = [r, g, b].map(c => c / 255);

  // Apply gamma correction
  const gamma = c => c <= 0.03928
    ? c / 12.92
    : Math.pow((c + 0.055) / 1.055, 2.4);

  const [R, G, B] = [rs, gs, bs].map(gamma);

  // Weighted sum (human eye sensitivity)
  return 0.2126 * R + 0.7152 * G + 0.0722 * B;
}

function contrastRatio(color1, color2) {
  const l1 = relativeLuminance(...color1);
  const l2 = relativeLuminance(...color2);
  const lighter = Math.max(l1, l2);
  const darker = Math.min(l1, l2);
  return (lighter + 0.05) / (darker + 0.05);
}

❌ FAILING EXAMPLE (from user screenshot):

┌─────────────────────────────────────────────┐
│  Background: #F5F2E8 (beige/cream)          │
│  Text: #C8FF00 (lime green)                 │
│                                             │
│     "Scan. Crawl. Match. Report."           │
│     ← UNREADABLE                            │
│                                             │
│  Calculated Ratio: ~1.5:1                   │
│  Required: 4.5:1 (normal) or 3:1 (large)    │
│  Verdict: FAIL by 3x                        │
└─────────────────────────────────────────────┘

✅ FIXED OPTIONS:
   • Darken text to #5A7300 → Ratio: 4.5:1
   • Darken background to #2A2A2A → Ratio: 12:1
   • Use dark green #1A4D00 → Ratio: 8:1

❌ COMMON FAILURE:
   Background: #FFFFFF
   Text: #AAAAAA (light gray)
   Ratio: 2.3:1 ← FAIL

✅ FIXES:
   • Text: #767676 → Ratio: 4.5:1 (minimum AA)
   • Text: #595959 → Ratio: 7:1 (AAA)

❌ DECEPTIVE FAILURE:
   Background: #FFF8E7 (warm white)
   Text: #FF6B6B (coral/salmon)
   Ratio: 2.8:1 ← FAIL (looks "colorful" but fails)

✅ FIXES:
   • Text: #C62828 (darker red) → Ratio: 5.2:1
   • Text: #8B0000 (dark red) → Ratio: 8.1:1

❌ "MINIMALIST" FAILURE:
   Background: #FAFAFA
   Text: #E0E0E0
   Ratio: 1.3:1 ← SEVERELY FAILING

This is NOT minimalism. This is inaccessible.

✅ MINIMALIST + ACCESSIBLE:
   Background: #FAFAFA
   Text: #616161 → Ratio: 5.7:1

❌ COMMON FORM FAILURE:
   Input background: #FFFFFF
   Placeholder: #CCCCCC
   Ratio: 1.6:1 ← FAIL

✅ FIX:
   Placeholder: #757575 → Ratio: 4.6:1

❌ VARIABLE CONTRAST:
   Gradient: #FFFFFF → #000080
   Text: #FFFFFF (fixed)

   Top of gradient: 1:1 (invisible!)
   Bottom of gradient: 8.6:1 (good)

✅ SOLUTIONS:
   • Add text shadow/outline
   • Use semi-transparent overlay behind text
   • Ensure ALL gradient stops pass contrast

# Find all color declarations
grep -E "(color:|background:|#[0-9a-fA-F]{3,8}|rgb|hsl)" styles.css

# Find text/bg color classes
grep -E "(text-|bg-)" *.tsx *.jsx

# Contrast Audit Report

## Summary
- Total color pairs tested: X
- Passing (AA): Y
- Failing: Z
- Critical failures (<2:1): N

## Failures by Severity

### Critical (Ratio < 2:1)
| Location | Foreground | Background | Ratio | Required | Fix |
|----------|------------|------------|-------|----------|-----|
| Hero tagline | #C8FF00 | #F5F2E8 | 1.5:1 | 3:1 | #5A7300 |

### Moderate (Ratio 2:1 - 3:1)
...

### Minor (Ratio 3:1 - 4.5:1, normal text only)
...

## Recommended Fixes
[Specific color replacements with new ratios]

// Chrome DevTools: Elements → Styles → hover color swatch
// Shows contrast ratio automatically

// Firefox: Accessibility Inspector
// Shows color contrast issues

// axe-core (popular a11y testing library)
const axe = require('axe-core');
axe.run(document, { rules: ['color-contrast'] });

// Lighthouse (built into Chrome)
// Performance → Accessibility → Color contrast

# Lighthouse CLI
npx lighthouse https://example.com --only-categories=accessibility

# Pa11y
npx pa11y https://example.com

AUDIT RESULT: CRITICAL FAILURE

Element: Hero tagline "Scan. Crawl. Match. Report."
Foreground: ~#C8FF00 (lime green)
Background: ~#F5F2E8 (beige)
Calculated Ratio: ~1.5:1
Required (large text): 3:1
Required (normal text): 4.5:1
Status: ❌ FAILS BY 2-3x

RECOMMENDED FIXES:
1. Darken text to #5A7300 (olive) → 4.8:1 ✓
2. Darken text to #3D5C00 (dark olive) → 7.1:1 ✓✓
3. Keep lime, darken BG to #3D3D3D → 8.2:1 ✓✓
4. Use #1B5E20 (dark green) → 8.4:1 ✓✓