Generated by SassMeister.com.

input.scss

@function to-number($value) {
  @if type-of($value) == 'number' {
    @return $value;
  } @else if type-of($value) != 'string' {
    @error 'Value for `to-number` should be a number or a string.';
  }

  $result: 0;
  $digits: 0;
  $minus: str-slice($value, 1, 1) == '-';
  $numbers: ('0': 0, '1': 1, '2': 2, '3': 3, '4': 4, '5': 5, '6': 6, '7': 7, '8': 8, '9': 9);

  @for $i from if($minus, 2, 1) through str-length($value) {
    $character: str-slice($value, $i, $i);

    @if (index(map-keys($numbers), $character) or $character == '.') {
      @if $character == '.' {
        $digits: 1; 
      } @else if $digits == 0 {
        $result: $result * 10 + map-get($numbers, $character);  
      } @else {
        $digits: $digits * 10;
        $result: $result + map-get($numbers, $character) / $digits;
      }
    }
  }

  @return if($minus, -$result, $result);;
}

@mixin rgbToXT256($colorNum){
    $zero: 0;
    $rStr: str-slice($colorNum,1,1);
    $rColor: ($zero+to-number($rStr) / 5) * 255;
    $gStr: str-slice($colorNum,2,2);
    $gColor: ($zero+to-number($gStr) / 5) * 255;
    $bStr: str-slice($colorNum,3,3);
    $bColor: ($zero+to-number($bStr) / 5) * 255;
  
    $color: rgb($rColor, $gColor, $bColor);
    background-color: $color;
    $rFColor: (5 - to-number($rStr) / 5) * 255;
    $gFColor: (5 - to-number($gStr) / 5) * 255;
    $bFColor: (5 - to-number($bStr) / 5) * 255;
  
    color: invert(grayscale($color), $weight: 100);
    
}
body {
    height: 100%;
}

@for $x from 0 through 5 {
    @for $y from 0 through 5 {
        @for $z from 0 through 5 {
            .color-#{$x}#{$y}#{$z}{
               @include rgbToXT256("#{$x}#{$y}#{$z}") 
            }
        }
    }
}

markup.html

<div class="color-500">
    Hello World
</div>

output.css

body {
  height: 100%;
}

.color-000 {
  background-color: black;
  color: white;
}

.color-001 {
  background-color: #000033;
  color: #e5e5e5;
}

.color-002 {
  background-color: #000066;
  color: #cccccc;
}

.color-003 {
  background-color: #000099;
  color: #b2b2b2;
}

.color-004 {
  background-color: #0000cc;
  color: #999999;
}

.color-005 {
  background-color: blue;
  color: #7f7f7f;
}

.color-010 {
  background-color: #003300;
  color: #e5e5e5;
}

.color-011 {
  background-color: #003333;
  color: #e5e5e5;
}

.color-012 {
  background-color: #003366;
  color: #cccccc;
}

.color-013 {
  background-color: #003399;
  color: #b2b2b2;
}

.color-014 {
  background-color: #0033cc;
  color: #999999;
}

.color-015 {
  background-color: #0033ff;
  color: #7f7f7f;
}

.color-020 {
  background-color: #006600;
  color: #cccccc;
}

.color-021 {
  background-color: #006633;
  color: #cccccc;
}

.color-022 {
  background-color: #006666;
  color: #cccccc;
}

.color-023 {
  background-color: #006699;
  color: #b2b2b2;
}

.color-024 {
  background-color: #0066cc;
  color: #999999;
}

.color-025 {
  background-color: #0066ff;
  color: #7f7f7f;
}

.color-030 {
  background-color: #009900;
  color: #b2b2b2;
}

.color-031 {
  background-color: #009933;
  color: #b2b2b2;
}

.color-032 {
  background-color: #009966;
  color: #b2b2b2;
}

.color-033 {
  background-color: #009999;
  color: #b2b2b2;
}

.color-034 {
  background-color: #0099cc;
  color: #999999;
}

.color-035 {
  background-color: #0099ff;
  color: #7f7f7f;
}

.color-040 {
  background-color: #00cc00;
  color: #999999;
}

.color-041 {
  background-color: #00cc33;
  color: #999999;
}

.color-042 {
  background-color: #00cc66;
  color: #999999;
}

.color-043 {
  background-color: #00cc99;
  color: #999999;
}

.color-044 {
  background-color: #00cccc;
  color: #999999;
}

.color-045 {
  background-color: #00ccff;
  color: #7f7f7f;
}

.color-050 {
  background-color: lime;
  color: #7f7f7f;
}

.color-051 {
  background-color: #00ff33;
  color: #7f7f7f;
}

.color-052 {
  background-color: #00ff66;
  color: #7f7f7f;
}

.color-053 {
  background-color: #00ff99;
  color: #7f7f7f;
}

.color-054 {
  background-color: #00ffcc;
  color: #7f7f7f;
}

.color-055 {
  background-color: aqua;
  color: #7f7f7f;
}

.color-100 {
  background-color: #330000;
  color: #e5e5e5;
}

.color-101 {
  background-color: #330033;
  color: #e5e5e5;
}

.color-102 {
  background-color: #330066;
  color: #cccccc;
}

.color-103 {
  background-color: #330099;
  color: #b2b2b2;
}

.color-104 {
  background-color: #3300cc;
  color: #999999;
}

.color-105 {
  background-color: #3300ff;
  color: #7f7f7f;
}

.color-110 {
  background-color: #333300;
  color: #e5e5e5;
}

.color-111 {
  background-color: #333333;
  color: #cccccc;
}

.color-112 {
  background-color: #333366;
  color: #b2b2b2;
}

.color-113 {
  background-color: #333399;
  color: #999999;
}

.color-114 {
  background-color: #3333cc;
  color: #7f7f7f;
}

.color-115 {
  background-color: #3333ff;
  color: #666666;
}

.color-120 {
  background-color: #336600;
  color: #cccccc;
}

.color-121 {
  background-color: #336633;
  color: #b2b2b2;
}

.color-122 {
  background-color: #336666;
  color: #b2b2b2;
}

.color-123 {
  background-color: #336699;
  color: #999999;
}

.color-124 {
  background-color: #3366cc;
  color: #7f7f7f;
}

.color-125 {
  background-color: #3366ff;
  color: #666666;
}

.color-130 {
  background-color: #339900;
  color: #b2b2b2;
}

.color-131 {
  background-color: #339933;
  color: #999999;
}

.color-132 {
  background-color: #339966;
  color: #999999;
}

.color-133 {
  background-color: #339999;
  color: #999999;
}

.color-134 {
  background-color: #3399cc;
  color: #7f7f7f;
}

.color-135 {
  background-color: #3399ff;
  color: #666666;
}

.color-140 {
  background-color: #33cc00;
  color: #999999;
}

.color-141 {
  background-color: #33cc33;
  color: #7f7f7f;
}

.color-142 {
  background-color: #33cc66;
  color: #7f7f7f;
}

.color-143 {
  background-color: #33cc99;
  color: #7f7f7f;
}

.color-144 {
  background-color: #33cccc;
  color: #7f7f7f;
}

.color-145 {
  background-color: #33ccff;
  color: #666666;
}

.color-150 {
  background-color: #33ff00;
  color: #7f7f7f;
}

.color-151 {
  background-color: #33ff33;
  color: #666666;
}

.color-152 {
  background-color: #33ff66;
  color: #666666;
}

.color-153 {
  background-color: #33ff99;
  color: #666666;
}

.color-154 {
  background-color: #33ffcc;
  color: #666666;
}

.color-155 {
  background-color: #33ffff;
  color: #666666;
}

.color-200 {
  background-color: #660000;
  color: #cccccc;
}

.color-201 {
  background-color: #660033;
  color: #cccccc;
}

.color-202 {
  background-color: #660066;
  color: #cccccc;
}

.color-203 {
  background-color: #660099;
  color: #b2b2b2;
}

.color-204 {
  background-color: #6600cc;
  color: #999999;
}

.color-205 {
  background-color: #6600ff;
  color: #7f7f7f;
}

.color-210 {
  background-color: #663300;
  color: #cccccc;
}

.color-211 {
  background-color: #663333;
  color: #b2b2b2;
}

.color-212 {
  background-color: #663366;
  color: #b2b2b2;
}

.color-213 {
  background-color: rebeccapurple;
  color: #999999;
}

.color-214 {
  background-color: #6633cc;
  color: #7f7f7f;
}

.color-215 {
  background-color: #6633ff;
  color: #666666;
}

.color-220 {
  background-color: #666600;
  color: #cccccc;
}

.color-221 {
  background-color: #666633;
  color: #b2b2b2;
}

.color-222 {
  background-color: #666666;
  color: #999999;
}

.color-223 {
  background-color: #666699;
  color: #7f7f7f;
}

.color-224 {
  background-color: #6666cc;
  color: #666666;
}

.color-225 {
  background-color: #6666ff;
  color: #4c4c4c;
}

.color-230 {
  background-color: #669900;
  color: #b2b2b2;
}

.color-231 {
  background-color: #669933;
  color: #999999;
}

.color-232 {
  background-color: #669966;
  color: #7f7f7f;
}

.color-233 {
  background-color: #669999;
  color: #7f7f7f;
}

.color-234 {
  background-color: #6699cc;
  color: #666666;
}

.color-235 {
  background-color: #6699ff;
  color: #4c4c4c;
}

.color-240 {
  background-color: #66cc00;
  color: #999999;
}

.color-241 {
  background-color: #66cc33;
  color: #7f7f7f;
}

.color-242 {
  background-color: #66cc66;
  color: #666666;
}

.color-243 {
  background-color: #66cc99;
  color: #666666;
}

.color-244 {
  background-color: #66cccc;
  color: #666666;
}

.color-245 {
  background-color: #66ccff;
  color: #4c4c4c;
}

.color-250 {
  background-color: #66ff00;
  color: #7f7f7f;
}

.color-251 {
  background-color: #66ff33;
  color: #666666;
}

.color-252 {
  background-color: #66ff66;
  color: #4c4c4c;
}

.color-253 {
  background-color: #66ff99;
  color: #4c4c4c;
}

.color-254 {
  background-color: #66ffcc;
  color: #4c4c4c;
}

.color-255 {
  background-color: #66ffff;
  color: #4c4c4c;
}

.color-300 {
  background-color: #990000;
  color: #b2b2b2;
}

.color-301 {
  background-color: #990033;
  color: #b2b2b2;
}

.color-302 {
  background-color: #990066;
  color: #b2b2b2;
}

.color-303 {
  background-color: #990099;
  color: #b2b2b2;
}

.color-304 {
  background-color: #9900cc;
  color: #999999;
}

.color-305 {
  background-color: #9900ff;
  color: #7f7f7f;
}

.color-310 {
  background-color: #993300;
  color: #b2b2b2;
}

.color-311 {
  background-color: #993333;
  color: #999999;
}

.color-312 {
  background-color: #993366;
  color: #999999;
}

.color-313 {
  background-color: #993399;
  color: #999999;
}

.color-314 {
  background-color: #9933cc;
  color: #7f7f7f;
}

.color-315 {
  background-color: #9933ff;
  color: #666666;
}

.color-320 {
  background-color: #996600;
  color: #b2b2b2;
}

.color-321 {
  background-color: #996633;
  color: #999999;
}

.color-322 {
  background-color: #996666;
  color: #7f7f7f;
}

.color-323 {
  background-color: #996699;
  color: #7f7f7f;
}

.color-324 {
  background-color: #9966cc;
  color: #666666;
}

.color-325 {
  background-color: #9966ff;
  color: #4c4c4c;
}

.color-330 {
  background-color: #999900;
  color: #b2b2b2;
}

.color-331 {
  background-color: #999933;
  color: #999999;
}

.color-332 {
  background-color: #999966;
  color: #7f7f7f;
}

.color-333 {
  background-color: #999999;
  color: #666666;
}

.color-334 {
  background-color: #9999cc;
  color: #4c4c4c;
}

.color-335 {
  background-color: #9999ff;
  color: #333333;
}

.color-340 {
  background-color: #99cc00;
  color: #999999;
}

.color-341 {
  background-color: #99cc33;
  color: #7f7f7f;
}

.color-342 {
  background-color: #99cc66;
  color: #666666;
}

.color-343 {
  background-color: #99cc99;
  color: #4c4c4c;
}

.color-344 {
  background-color: #99cccc;
  color: #4c4c4c;
}

.color-345 {
  background-color: #99ccff;
  color: #333333;
}

.color-350 {
  background-color: #99ff00;
  color: #7f7f7f;
}

.color-351 {
  background-color: #99ff33;
  color: #666666;
}

.color-352 {
  background-color: #99ff66;
  color: #4c4c4c;
}

.color-353 {
  background-color: #99ff99;
  color: #333333;
}

.color-354 {
  background-color: #99ffcc;
  color: #333333;
}

.color-355 {
  background-color: #99ffff;
  color: #333333;
}

.color-400 {
  background-color: #cc0000;
  color: #999999;
}

.color-401 {
  background-color: #cc0033;
  color: #999999;
}

.color-402 {
  background-color: #cc0066;
  color: #999999;
}

.color-403 {
  background-color: #cc0099;
  color: #999999;
}

.color-404 {
  background-color: #cc00cc;
  color: #999999;
}

.color-405 {
  background-color: #cc00ff;
  color: #7f7f7f;
}

.color-410 {
  background-color: #cc3300;
  color: #999999;
}

.color-411 {
  background-color: #cc3333;
  color: #7f7f7f;
}

.color-412 {
  background-color: #cc3366;
  color: #7f7f7f;
}

.color-413 {
  background-color: #cc3399;
  color: #7f7f7f;
}

.color-414 {
  background-color: #cc33cc;
  color: #7f7f7f;
}

.color-415 {
  background-color: #cc33ff;
  color: #666666;
}

.color-420 {
  background-color: #cc6600;
  color: #999999;
}

.color-421 {
  background-color: #cc6633;
  color: #7f7f7f;
}

.color-422 {
  background-color: #cc6666;
  color: #666666;
}

.color-423 {
  background-color: #cc6699;
  color: #666666;
}

.color-424 {
  background-color: #cc66cc;
  color: #666666;
}

.color-425 {
  background-color: #cc66ff;
  color: #4c4c4c;
}

.color-430 {
  background-color: #cc9900;
  color: #999999;
}

.color-431 {
  background-color: #cc9933;
  color: #7f7f7f;
}

.color-432 {
  background-color: #cc9966;
  color: #666666;
}

.color-433 {
  background-color: #cc9999;
  color: #4c4c4c;
}

.color-434 {
  background-color: #cc99cc;
  color: #4c4c4c;
}

.color-435 {
  background-color: #cc99ff;
  color: #333333;
}

.color-440 {
  background-color: #cccc00;
  color: #999999;
}

.color-441 {
  background-color: #cccc33;
  color: #7f7f7f;
}

.color-442 {
  background-color: #cccc66;
  color: #666666;
}

.color-443 {
  background-color: #cccc99;
  color: #4c4c4c;
}

.color-444 {
  background-color: #cccccc;
  color: #333333;
}

.color-445 {
  background-color: #ccccff;
  color: #191919;
}

.color-450 {
  background-color: #ccff00;
  color: #7f7f7f;
}

.color-451 {
  background-color: #ccff33;
  color: #666666;
}

.color-452 {
  background-color: #ccff66;
  color: #4c4c4c;
}

.color-453 {
  background-color: #ccff99;
  color: #333333;
}

.color-454 {
  background-color: #ccffcc;
  color: #191919;
}

.color-455 {
  background-color: #ccffff;
  color: #191919;
}

.color-500 {
  background-color: red;
  color: #7f7f7f;
}

.color-501 {
  background-color: #ff0033;
  color: #7f7f7f;
}

.color-502 {
  background-color: #ff0066;
  color: #7f7f7f;
}

.color-503 {
  background-color: #ff0099;
  color: #7f7f7f;
}

.color-504 {
  background-color: #ff00cc;
  color: #7f7f7f;
}

.color-505 {
  background-color: fuchsia;
  color: #7f7f7f;
}

.color-510 {
  background-color: #ff3300;
  color: #7f7f7f;
}

.color-511 {
  background-color: #ff3333;
  color: #666666;
}

.color-512 {
  background-color: #ff3366;
  color: #666666;
}

.color-513 {
  background-color: #ff3399;
  color: #666666;
}

.color-514 {
  background-color: #ff33cc;
  color: #666666;
}

.color-515 {
  background-color: #ff33ff;
  color: #666666;
}

.color-520 {
  background-color: #ff6600;
  color: #7f7f7f;
}

.color-521 {
  background-color: #ff6633;
  color: #666666;
}

.color-522 {
  background-color: #ff6666;
  color: #4c4c4c;
}

.color-523 {
  background-color: #ff6699;
  color: #4c4c4c;
}

.color-524 {
  background-color: #ff66cc;
  color: #4c4c4c;
}

.color-525 {
  background-color: #ff66ff;
  color: #4c4c4c;
}

.color-530 {
  background-color: #ff9900;
  color: #7f7f7f;
}

.color-531 {
  background-color: #ff9933;
  color: #666666;
}

.color-532 {
  background-color: #ff9966;
  color: #4c4c4c;
}

.color-533 {
  background-color: #ff9999;
  color: #333333;
}

.color-534 {
  background-color: #ff99cc;
  color: #333333;
}

.color-535 {
  background-color: #ff99ff;
  color: #333333;
}

.color-540 {
  background-color: #ffcc00;
  color: #7f7f7f;
}

.color-541 {
  background-color: #ffcc33;
  color: #666666;
}

.color-542 {
  background-color: #ffcc66;
  color: #4c4c4c;
}

.color-543 {
  background-color: #ffcc99;
  color: #333333;
}

.color-544 {
  background-color: #ffcccc;
  color: #191919;
}

.color-545 {
  background-color: #ffccff;
  color: #191919;
}

.color-550 {
  background-color: yellow;
  color: #7f7f7f;
}

.color-551 {
  background-color: #ffff33;
  color: #666666;
}

.color-552 {
  background-color: #ffff66;
  color: #4c4c4c;
}

.color-553 {
  background-color: #ffff99;
  color: #333333;
}

.color-554 {
  background-color: #ffffcc;
  color: #191919;
}

.color-555 {
  background-color: white;
  color: black;
}

settings.json

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