Generated by SassMeister.com.

input.scss

$primary: #0d6efd;

@function shade-color($color, $weight) {
  @return mix(black, $color, $weight);
}

a {
    color: darken($primary, 20%);
}

b { 
    color: shade-color($primary, 20%);
}

output.css

a {
  color: #0143a3;
}

b {
  color: #0a58ca;
}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.26.11",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}