#1C3716

CSS

:root {
  --dark-serpent: #1c3716;
  --dark-serpent-rgb: 28 55 22;
  --dark-serpent-oklch: oklch(0.306 0.065 140);
}

.element {
  color: var(--dark-serpent);
  background-color: hsl(109 43% 15%);
  border-color: oklch(0.306 0.065 140);
}

Tailwind CSS v4

@theme {
  --color-dark-serpent: #1c3716;
  --color-dark-serpent-50: #ebfae9;
  --color-dark-serpent-100: #dceeda;
  --color-dark-serpent-200: #c5dcc2;
  --color-dark-serpent-300: #a5c0a2;
  --color-dark-serpent-400: #8aa884;
  --color-dark-serpent-500: #6f9168;
  --color-dark-serpent-600: #5e7b58;
  --color-dark-serpent-700: #4b6246;
  --color-dark-serpent-800: #374832;
  --color-dark-serpent-900: #263222;
  --color-dark-serpent-950: #141e11;
}

SCSS

$dark-serpent: #1c3716;
$dark-serpent-rgb: 28, 55, 22;
$dark-serpent-light: mix(#fff, $dark-serpent, 20%);
$dark-serpent-dark: mix(#000, $dark-serpent, 20%);

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