#BB4534

CSS

:root {
  --crimson-boy: #bb4534;
  --crimson-boy-rgb: 187 69 52;
  --crimson-boy-oklch: oklch(0.55 0.156 30.8);
}

.element {
  color: var(--crimson-boy);
  background-color: hsl(8 56% 47%);
  border-color: oklch(0.55 0.156 30.8);
}

Tailwind CSS v4

@theme {
  --color-crimson-boy: #bb4534;
  --color-crimson-boy-50: #ffe6d9;
  --color-crimson-boy-100: #ffd6c7;
  --color-crimson-boy-200: #ffbcaa;
  --color-crimson-boy-300: #fc9983;
  --color-crimson-boy-400: #ec7764;
  --color-crimson-boy-500: #da5441;
  --color-crimson-boy-600: #b84838;
  --color-crimson-boy-700: #943a2c;
  --color-crimson-boy-800: #6e2821;
  --color-crimson-boy-900: #4e1b16;
  --color-crimson-boy-950: #330b07;
}

SCSS

$crimson-boy: #bb4534;
$crimson-boy-rgb: 187, 69, 52;
$crimson-boy-light: mix(#fff, $crimson-boy, 20%);
$crimson-boy-dark: mix(#000, $crimson-boy, 20%);

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