#637D45

CSS

:root {
  --beyond-the-pines: #637d45;
  --beyond-the-pines-rgb: 99 125 69;
  --beyond-the-pines-oklch: oklch(0.555 0.086 129.2);
}

.element {
  color: var(--beyond-the-pines);
  background-color: hsl(88 29% 38%);
  border-color: oklch(0.555 0.086 129.2);
}

Tailwind CSS v4

@theme {
  --color-beyond-the-pines: #637d45;
  --color-beyond-the-pines-50: #ecfbe1;
  --color-beyond-the-pines-100: #deeed1;
  --color-beyond-the-pines-200: #c7dcb6;
  --color-beyond-the-pines-300: #a8c193;
  --color-beyond-the-pines-400: #8ea972;
  --color-beyond-the-pines-500: #749152;
  --color-beyond-the-pines-600: #627b46;
  --color-beyond-the-pines-700: #4f6238;
  --color-beyond-the-pines-800: #3a4826;
  --color-beyond-the-pines-900: #28321a;
  --color-beyond-the-pines-950: #161e0a;
}

SCSS

$beyond-the-pines: #637d45;
$beyond-the-pines-rgb: 99, 125, 69;
$beyond-the-pines-light: mix(#fff, $beyond-the-pines, 20%);
$beyond-the-pines-dark: mix(#000, $beyond-the-pines, 20%);

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