#637C4B

CSS

:root {
  --beyond-the-pines: #637c4b;
  --beyond-the-pines-rgb: 99 124 75;
  --beyond-the-pines-oklch: oklch(0.554 0.077 130.6);
}

.element {
  color: var(--beyond-the-pines);
  background-color: hsl(91 25% 39%);
  border-color: oklch(0.554 0.077 130.6);
}

Tailwind CSS v4

@theme {
  --color-beyond-the-pines: #637c4b;
  --color-beyond-the-pines-50: #edfae4;
  --color-beyond-the-pines-100: #deeed4;
  --color-beyond-the-pines-200: #c8dcba;
  --color-beyond-the-pines-300: #a8c098;
  --color-beyond-the-pines-400: #8fa878;
  --color-beyond-the-pines-500: #749159;
  --color-beyond-the-pines-600: #637a4c;
  --color-beyond-the-pines-700: #4f623d;
  --color-beyond-the-pines-800: #3a482a;
  --color-beyond-the-pines-900: #28321c;
  --color-beyond-the-pines-950: #161e0d;
}

SCSS

$beyond-the-pines: #637c4b;
$beyond-the-pines-rgb: 99, 124, 75;
$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);
}