Fix contrast calculation

code.js

function calculateContrast(foreground, alpha, backgound) {
  const foregroundLuminance = calculateLuminance(foreground) + 0.05
  const backgroundLuminance = calculateLuminance(backgound) + 0.05
  let contrast = foregroundLuminance / backgroundLuminance
  if (backgroundLuminance > foregroundLuminance) {
    contrast = 1 / contrast
  }
  // round to two decimal places
  contrast = Math.floor(contrast * 100) / 100
  return contrast
}