picocss/scss/helpers/_functions.scss

@use "sass:color";
@use "sass:string";

// Display color as RGB
@function display-rgb($color) {
  @return string.unquote(
    "rgb(" + color.channel($color, "red", $space: rgb) + ", " +
      color.channel($color, "green", $space: rgb) + ", " +
      color.channel($color, "blue", $space: rgb) + ")"
  );
}

// Generate a shadow layer
@function shadow-layer($elevation, $blur, $opacity, $color) {
  @return #{($elevation * 0.5)} #{$elevation} #{$blur} #{rgba($color, $opacity)};
}

// Generate a shadow with 7 layers
@function shadow($color) {
  $box-shadow-elevation: 1rem;
  $box-shadow-blur-strength: 6rem;
  $box-shadow-opacity: 0.06;

  @return shadow-layer(
      $box-shadow-elevation * 0.029,
      $box-shadow-blur-strength * 0.029,
      $box-shadow-opacity * 0.283,
      $color
    ),
    shadow-layer(
      $box-shadow-elevation * 0.067,
      $box-shadow-blur-strength * 0.067,
      $box-shadow-opacity * 0.4,
      $color
    ),
    shadow-layer(
      $box-shadow-elevation * 0.125,
      $box-shadow-blur-strength * 0.125,
      $box-shadow-opacity * 0.5,
      $color
    ),
    shadow-layer(
      $box-shadow-elevation * 0.225,
      $box-shadow-blur-strength * 0.225,
      $box-shadow-opacity * 0.6,
      $color
    ),
    shadow-layer(
      $box-shadow-elevation * 0.417,
      $box-shadow-blur-strength * 0.417,
      $box-shadow-opacity * 0.717,
      $color
    ),
    shadow-layer($box-shadow-elevation, $box-shadow-blur-strength, $box-shadow-opacity, $color),
    0 0 0 0.0625rem #{rgba($color, ($box-shadow-opacity * 0.25))};
}

// tint-color, shade-color, and shift-color
// borrowed from Bootstrap 5.3.3
// MIT License github.com/twbs/bootstrap
// Tint a color: mix a color with white
@function tint-color($color, $weight) {
  @return mix(white, $color, $weight);
}

// Shade a color: mix a color with black
@function shade-color($color, $weight) {
  @return mix(black, $color, $weight);
}

// Shade the color if the weight is positive, else tint it
@function shift-color($color, $weight) {
  @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
}