This mixin calculates the closest best possible contrast for a given text color according to WCAG (Web Content Accessibility Guidelines) standards.

gistfile1.txt

@mixin best-contrast($text-color, $bg-color, $level) {
  $lum1: luminance($text-color);
  $lum2: luminance($bg-color);
  $contrast: $lum1 / $lum2;
  @if $contrast < 1 {
    $contrast: 1 / $contrast;
  }
  @if $level == AA {
    @if $contrast < 4.5 {
      // Text color does not meet AA contrast ratio, adjust color
      // ...
    }
  } @else if $level == AAA {
    @if $contrast < 7 {
      // Text color does not meet AAA contrast ratio, adjust color
      // ...
    }
  }
}