codeninjasuk.github.io/_sass/minimal-mistakes/vendor/breakpoint/_helpers.scss

//////////////////////////////
// Converts the input value to Base EMs
//////////////////////////////
@function breakpoint-to-base-em($value) {
  $value-unit: unit($value);

  // Will convert relative EMs into root EMs.
  @if breakpoint-get('base font size') and type-of(breakpoint-get('base font size')) == 'number' and $value-unit == 'em' {
    $base-unit: unit(breakpoint-get('base font size'));

    @if $base-unit == 'px' or $base-unit == '%' or $base-unit == 'em' or $base-unit == 'pt' {
      @return base-conversion($value) / base-conversion(breakpoint-get('base font size')) * 1em;
    }
    @else {
      @warn '#{breakpoint-get(\'base font size\')} is not set in valid units for font size!';
      @return false;
    }
  }
  @else {
    @return base-conversion($value);
  }
}

@function base-conversion($value) {
  $unit: unit($value);

  @if $unit == 'px' {
    @return $value / 16px * 1em;
  }
  @else if $unit == '%' {
    @return $value / 100% * 1em;
  }
  @else if $unit == 'em' {
    @return $value;
  }
  @else if $unit == 'pt' {
    @return $value / 12pt * 1em;
  }
  @else {
    @return $value;
//    @warn 'Everything is terrible! What have you done?!';
  }
}

//////////////////////////////
// Returns whether the feature can have a min/max pair
//////////////////////////////
$breakpoint-min-max-features: 'color',
                              'color-index',
                              'aspect-ratio',
                              'device-aspect-ratio',
                              'device-height',
                              'device-width',
                              'height',
                              'monochrome',
                              'resolution',
                              'width';

@function breakpoint-min-max($feature) {
  @each $item in $breakpoint-min-max-features {
    @if $feature == $item {
      @return true;
    }
  }
  @return false;
}

//////////////////////////////
// Returns whether the feature can have a string value
//////////////////////////////
$breakpoint-string-features:  'orientation',
                              'scan',
                              'color',
                              'aspect-ratio',
                              'device-aspect-ratio',
                              'pointer',
                              'luminosity';

@function breakpoint-string-value($feature) {
  @each $item in $breakpoint-string-features {
    @if breakpoint-min-max($item) {
      @if $feature == 'min-#{$item}' or $feature == 'max-#{$item}' {
        @return true;
      }
    }
    @else if $feature == $item {
      @return true;
    }
  }
  @return false;
}

//////////////////////////////
// Returns whether the feature is a media type
//////////////////////////////
$breakpoint-media-types:  'all',
                          'braille',
                          'embossed',
                          'handheld',
                          'print',
                          'projection',
                          'screen',
                          'speech',
                          'tty',
                          'tv';

@function breakpoint-is-media($feature) {
  @each $media in $breakpoint-media-types {
    @if ($feature == $media) or ($feature == 'not #{$media}') or ($feature == 'only #{$media}') {
      @return true;
    }
  }

  @return false;
}

//////////////////////////////
// Returns whether the feature can stand alone
//////////////////////////////
$breakpoint-single-string-features: 'color',
                                    'color-index',
                                    'grid',
                                    'monochrome';

@function breakpoint-single-string($feature) {
  @each $item in $breakpoint-single-string-features {
    @if $feature == $item {
      @return true;
    }
  }
  @return false;
}

//////////////////////////////
// Returns whether the feature
//////////////////////////////
@function breakpoint-is-resolution($feature) {
  $resolutions: 'device-pixel-ratio', 'dpr';

  @if breakpoint-get('transform resolutions') {
    $resolutions: append($resolutions, 'resolution');
  }

  @each $reso in $resolutions {
    @if index($feature, $reso) or index($feature, 'min-#{$reso}') or index($feature, 'max-#{$reso}') {
      @return true;
    }
  }

  @return false;
}