#E91831

CSS

:root {
  --transfusion: #e91831;
  --transfusion-rgb: 233 24 49;
  --transfusion-oklch: oklch(0.595 0.232 24);
}

.element {
  color: var(--transfusion);
  background-color: hsl(353 83% 50%);
  border-color: oklch(0.595 0.232 24);
}

Tailwind CSS v4

@theme {
  --color-transfusion: #e91831;
  --color-transfusion-50: #ffdcd3;
  --color-transfusion-100: #ffcabf;
  --color-transfusion-200: #ffaba0;
  --color-transfusion-300: #ff8177;
  --color-transfusion-400: #ff5356;
  --color-transfusion-500: #fb002d;
  --color-transfusion-600: #d40628;
  --color-transfusion-700: #ab0a20;
  --color-transfusion-800: #800319;
  --color-transfusion-900: #5b0410;
  --color-transfusion-950: #3d0004;
}

SCSS

$transfusion: #e91831;
$transfusion-rgb: 233, 24, 49;
$transfusion-light: mix(#fff, $transfusion, 20%);
$transfusion-dark: mix(#000, $transfusion, 20%);

.element {
  color: $transfusion;
  box-shadow: 0 0 0 2px rgba($transfusion, 0.35);
}