bulma/sass/utilities/functions.sass

@function mergeColorMaps($bulma-colors, $custom-colors)
  // We return at least Bulma's hard-coded colors
  $merged-colors: $bulma-colors

  // We want a map as input
  @if type-of($custom-colors) == 'map'
    @each $name, $components in $custom-colors
      // The color name should be a string
      // and the components either a single color
      // or a colors list with at least one element
      @if type-of($name) == 'string' and (type-of($components) == 'list' or type-of($components) == 'color') and length($components) >= 1
        $color-base: null
        $value: null

        // The param can either be a single color
        // or a list of 2 colors
        @if type-of($components) == 'color'
          $color-base: $components
          $value: $components
        @else if type-of($components) == 'list'
          $color-base: nth($components, 1)
          $color-invert: null
          // Check if the invert color is provided,
          // otherwise compute it
          @if length($components) > 1
            $color-invert: nth($components, 2)
          @else
            $color-invert: findColorInvert($color-base)
          $value: ($color-base, $color-invert)

        // We only want to merge the map if the color base is an actual color
        @if type-of($color-base) == 'color'
          // We merge this colors elements as map with Bulma's colors map
          // (we can override them this way, no multiple definition for the same name)
          // $merged-colors: map_merge($merged-colors, ($name: ($color-base, $color-invert)))
          $merged-colors: map_merge($merged-colors, ($name: $value))

  @return $merged-colors

@function powerNumber($number, $exp)
  $value: 1
  @if $exp > 0
    @for $i from 1 through $exp
      $value: $value * $number
  @else if $exp < 0
    @for $i from 1 through -$exp
      $value: $value / $number
  @return $value

@function colorLuminance($color)
  $color-rgb: ('red': red($color),'green': green($color),'blue': blue($color))
  @each $name, $value in $color-rgb
    $adjusted: 0
    $value: $value / 255
    @if $value < 0.03928
      $value: $value / 12.92
    @else
      $value: ($value + .055) / 1.055
      $value: powerNumber($value, 2)
    $color-rgb: map-merge($color-rgb, ($name: $value))
  @return (map-get($color-rgb, 'red') * .2126) + (map-get($color-rgb, 'green') * .7152) + (map-get($color-rgb, 'blue') * .0722)

@function findColorInvert($color)
  @if (colorLuminance($color) > 0.55)
    @return rgba(#000, 0.7)
  @else
    @return #fff