#5B706C

CSS

:root {
  --dark-forest: #5b706c;
  --dark-forest-rgb: 91 112 108;
  --dark-forest-oklch: oklch(0.527 0.026 182.5);
}

.element {
  color: var(--dark-forest);
  background-color: hsl(169 10% 40%);
  border-color: oklch(0.527 0.026 182.5);
}

Tailwind CSS v4

@theme {
  --color-dark-forest: #5b706c;
  --color-dark-forest-50: #eef8f6;
  --color-dark-forest-100: #dfebe9;
  --color-dark-forest-200: #c9d8d5;
  --color-dark-forest-300: #aabcb9;
  --color-dark-forest-400: #8fa4a0;
  --color-dark-forest-500: #748c87;
  --color-dark-forest-600: #627673;
  --color-dark-forest-700: #4f5f5c;
  --color-dark-forest-800: #394543;
  --color-dark-forest-900: #27302e;
  --color-dark-forest-950: #151c1b;
}

SCSS

$dark-forest: #5b706c;
$dark-forest-rgb: 91, 112, 108;
$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);
}