Bootstrap/scss/_root.scss

:root {
  // Note: Custom variable values only support SassScript inside `#{}`.

  // Colors
  //
  // Generate palettes for full colors, grays, and theme colors.

  @each $color, $value in $colors {
    --#{$variable-prefix}#{$color}: #{$value};
  }

  @each $color, $value in $grays {
    --#{$variable-prefix}gray-#{$color}: #{$value};
  }

  @each $color, $value in $theme-colors {
    --#{$variable-prefix}#{$color}: #{$value};
  }

  @each $color, $value in $theme-colors-rgb {
    --#{$variable-prefix}#{$color}-rgb: #{$value};
  }

  --#{$variable-prefix}white-rgb: #{to-rgb($white)};
  --#{$variable-prefix}black-rgb: #{to-rgb($black)};
  --#{$variable-prefix}body-color-rgb: #{to-rgb($body-color)};
  --#{$variable-prefix}body-bg-rgb: #{to-rgb($body-bg)};

  // Fonts

  // Note: Use `inspect` for lists so that quoted items keep the quotes.
  // See https://github.com/sass/sass/issues/2383#issuecomment-336349172
  --#{$variable-prefix}font-sans-serif: #{inspect($font-family-sans-serif)};
  --#{$variable-prefix}font-monospace: #{inspect($font-family-monospace)};
  --#{$variable-prefix}gradient: #{$gradient};

  // Root and body
  // stylelint-disable custom-property-empty-line-before
  // scss-docs-start root-body-variables
  @if $font-size-root != null {
    --#{$variable-prefix}root-font-size: #{$font-size-root};
  }
  --#{$variable-prefix}body-font-family: #{$font-family-base};
  @include rfs($font-size-base, --#{$variable-prefix}body-font-size);
  --#{$variable-prefix}body-font-weight: #{$font-weight-base};
  --#{$variable-prefix}body-line-height: #{$line-height-base};
  --#{$variable-prefix}body-color: #{$body-color};
  @if $body-text-align != null {
    --#{$variable-prefix}body-text-align: #{$body-text-align};
  }
  --#{$variable-prefix}body-bg: #{$body-bg};
  // scss-docs-end root-body-variables
  // stylelint-enable custom-property-empty-line-before
}