naive-ui/styles/utils/color.scss

@function composite-color ($background-color, $color) {
  $background-color-alpha: alpha($background-color);
  @if $background-color-alpha != 1 {
    @error "[naive-ui/styles/composite-color]: background-color isn't opaque.";
  }
  $color-weight: percentage(alpha($color));
  $temp-color-1: scale-color($background-color, $lightness: -$color-weight);
  $temp-color-2: scale-color($color, $lightness: -(100% - $color-weight));
  @return rgb(
    red($temp-color-1) + red($temp-color-2),
    green($temp-color-1) + green($temp-color-2),
    blue($temp-color-1) + blue($temp-color-2)
  );
}