Generated by SassMeister.com.

input.scss

@use 'sass:color';
@use 'sass:math';

@function scale($v, $w, $n, $x) {
  @if ($w > 0) {
    $i: ($x - $v);
    $s: (($w * $s) / 100);
    $v: ($v + $s);
  } @else if ($w < 0) {
    $i: ($v - $n);
    $w: math.abs($w);
    $s: (($w * $s) / 100);
    $v: ($v - $s);
  } @else {
    $v: $v;
  }

  @return $v;
}

@function gen($c, $m, $h, $s, $l) {
    $ch: color.hue($c);
    $cs: color.saturation($c);
    $h: scale($ch, $h, 0, 360);
    $s: scale($cs, $s, 0, 100);
    
    $c: color.mix($m, $c, $l);
    $c: color.change($c, $hue: $h, $saturation: $s);
    
    @return $c;
}


$cb: #333;
$cbh: color.hue($cb);
$cbs: color.saturation($cb);
$cbl: color.lightness($cb);

$ct: #666;
$cth: color.hue($ct);
$cts: color.saturation($ct);
$ctl: color.lightness($ct);

$co: gen($cb, white, 0, 0, 25.0);
$coh: color.hue($co);
$cos: color.saturation($co);
$col: color.lightness($co);

debug {
    /* base */
    value: $cb;
    value: $cbh;
    value: $cbs;
    value: $cbl;
    /* target */
    value: $ct;
    value: $cth;
    value: $cts;
    value: $ctl;
    /* output */
    value: $co;
    value: $coh;
    value: $cos;
    value: $col;
    /* state */
    value-c: if(($co != $ct), 'fails', 'pass');
    value-h: if(($coh < $cth), 'inc hue', if(($coh > $cth), 'dec hue', 'pass'));
    value-s: if(($cos < $cts), 'inc sat', if(($cos > $cts), 'dec sat', 'pass'));
    value-l: if(($col < $ctl), 'inc lig', if(($col > $ctl), 'dec lig', 'pass'));
}

output.css

debug {
  /* base */
  value: #333;
  value: 0deg;
  value: 0%;
  value: 20%;
  /* target */
  value: #666;
  value: 0deg;
  value: 0%;
  value: 40%;
  /* output */
  value: #666666;
  value: 0deg;
  value: 0%;
  value: 40%;
  /* state */
  value-c: "pass";
  value-h: "pass";
  value-s: "pass";
  value-l: "pass";
}

settings.json

{
  "sass": {
    "compiler": "dart-sass/1.32.12",
    "extensions": {},
    "syntax": "SCSS",
    "outputStyle": "expanded"
  },
  "autoprefixer": false
}