#55726A

CSS

:root {
  --dark-forest: #55726a;
  --dark-forest-rgb: 85 114 106;
  --dark-forest-oklch: oklch(0.527 0.036 176);
}

.element {
  color: var(--dark-forest);
  background-color: hsl(163 15% 39%);
  border-color: oklch(0.527 0.036 176);
}

Tailwind CSS v4

@theme {
  --color-dark-forest: #55726a;
  --color-dark-forest-50: #ebf9f5;
  --color-dark-forest-100: #dcece8;
  --color-dark-forest-200: #c5dad4;
  --color-dark-forest-300: #a5beb7;
  --color-dark-forest-400: #89a69d;
  --color-dark-forest-500: #6d8e85;
  --color-dark-forest-600: #5d7871;
  --color-dark-forest-700: #4a605a;
  --color-dark-forest-800: #364741;
  --color-dark-forest-900: #25312d;
  --color-dark-forest-950: #131d1a;
}

SCSS

$dark-forest: #55726a;
$dark-forest-rgb: 85, 114, 106;
$dark-forest-light: mix(#fff, $dark-forest, 20%);
$dark-forest-dark: mix(#000, $dark-forest, 20%);

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