SCSS: компонент оповещения - изменить цвет SVG в зависимости от цвета фона?

Я хочу изменить цвет SVG кнопки «Закрыть» в зависимости от того, какой цвет используется в фоновом режиме. Я использую некоторые функции Sass * ($_luminance-list, color-contrast, contrast-ratio, luminance) для управления цветами.*

Пример Codepen:

codepen

Вот текущий результат:

Чего я хочу достичь:

Мой полный код включает функции, которые я использую.

$_luminance-list: .0008 .001 .0011 .0013 .0015 .0017 .002 .0022 .0025 .0027 .003 .0033 .0037 .004 .0044 .0048 .0052 .0056 .006 .0065 .007 .0075 .008 .0086 .0091 .0097 .0103 .011 .0116 .0123 .013 .0137 .0144 .0152 .016 .0168 .0176 .0185 .0194 .0203 .0212 .0222 .0232 .0242 .0252 .0262 .0273 .0284 .0296 .0307 .0319 .0331 .0343 .0356 .0369 .0382 .0395 .0409 .0423 .0437 .0452 .0467 .0482 .0497 .0513 .0529 .0545 .0561 .0578 .0595 .0612 .063 .0648 .0666 .0685 .0704 .0723 .0742 .0762 .0782 .0802 .0823 .0844 .0865 .0887 .0908 .0931 .0953 .0976 .0999 .1022 .1046 .107 .1095 .1119 .1144 .117 .1195 .1221 .1248 .1274 .1301 .1329 .1356 .1384 .1413 .1441 .147 .15 .1529 .1559 .159 .162 .1651 .1683 .1714 .1746 .1779 .1812 .1845 .1878 .1912 .1946 .1981 .2016 .2051 .2086 .2122 .2159 .2195 .2232 .227 .2307 .2346 .2384 .2423 .2462 .2502 .2542 .2582 .2623 .2664 .2705 .2747 .2789 .2831 .2874 .2918 .2961 .3005 .305 .3095 .314 .3185 .3231 .3278 .3325 .3372 .3419 .3467 .3515 .3564 .3613 .3663 .3712 .3763 .3813 .3864 .3916 .3968 .402 .4072 .4125 .4179 .4233 .4287 .4342 .4397 .4452 .4508 .4564 .4621 .4678 .4735 .4793 .4851 .491 .4969 .5029 .5089 .5149 .521 .5271 .5333 .5395 .5457 .552 .5583 .5647 .5711 .5776 .5841 .5906 .5972 .6038 .6105 .6172 .624 .6308 .6376 .6445 .6514 .6584 .6654 .6724 .6795 .6867 .6939 .7011 .7084 .7157 .7231 .7305 .7379 .7454 .7529 .7605 .7682 .7758 .7835 .7913 .7991 .807 .8148 .8228 .8308 .8388 .8469 .855 .8632 .8714 .8796 .8879 .8963 .9047 .9131 .9216 .9301 .9387 .9473 .956 .9647 .9734 .9823 .9911 1;

@function color-contrast($background, $color-contrast-dark: $color-contrast-dark, $color-contrast-light: $color-contrast-light, $min-contrast-ratio: $min-contrast-ratio) {
  $foregrounds: $color-contrast-light, $color-contrast-dark, $white, $black;
  $max-ratio: 0;
  $max-ratio-color: null;

  @each $color in $foregrounds {
    $contrast-ratio: contrast-ratio($background, $color);
    @if $contrast-ratio > $min-contrast-ratio {
      @return $color;
    } @else if $contrast-ratio > $max-ratio {
      $max-ratio: $contrast-ratio;
      $max-ratio-color: $color;
    }
  }

  @warn "Found no color leading to #{$min-contrast-ratio}:1 contrast ratio against #{$background}...";

  @return $max-ratio-color;
}

@function contrast-ratio($background, $foreground: $color-contrast-light) {
  $l1: luminance($background);
  $l2: luminance(opaque($background, $foreground));

  @return if($l1 > $l2, ($l1 + .05) / ($l2 + .05), ($l2 + .05) / ($l1 + .05));
}

@function luminance($color) {
  $rgb: (
    "r": red($color),
    "g": green($color),
    "b": blue($color)
  );

  @each $name, $value in $rgb {
    $value: if($value / 255 < .03928, $value / 255 / 12.92, nth($_luminance-list, $value + 1));
    $rgb: map-merge($rgb, ($name: $value));
  }

  @return (map-get($rgb, "r") * .2126) + (map-get($rgb, "g") * .7152) + (map-get($rgb, "b") * .0722);
}

@function opaque($background, $foreground) {
  @return mix(rgba($foreground, 1), $background, opacity($foreground) * 100);
}

@function tint-color($color, $weight) {
  @return mix(white, $color, $weight);
}

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

@function shift-color($color, $weight) {
  @return if($weight > 0, shade-color($color, $weight), tint-color($color, -$weight));
}

$white:          #ffffff       !default;
$black:          #000000       !default;

$min-contrast-ratio:   4.5                   !default;
$color-contrast-dark:  $black                !default;
$color-contrast-light: $white                !default;

$yellow: #ffc107 !default;

$theme-colors: () !default;
$theme-colors: map-merge(
    (
        "yellow":   yellow
    ),
    $theme-colors
);

@mixin alert-variant(
  $background,
  $border,
  $color: color-contrast($background)
) {
  color: $color;
  background-color: $background;
  border-color: $border;
  
  .btn-close {
      filter: invert(1) grayscale(100%) brightness(200%);
  }
}

@each $color, $value in $theme-colors {
  .alert-#{$color} {
    @include alert-variant($value, $value);
  }
}