#637F3F

CSS

:root {
  --beyond-the-pines: #637f3f;
  --beyond-the-pines-rgb: 99 127 63;
  --beyond-the-pines-oklch: oklch(0.559 0.096 128.6);
}

.element {
  color: var(--beyond-the-pines);
  background-color: hsl(86 34% 37%);
  border-color: oklch(0.559 0.096 128.6);
}

Tailwind CSS v4

@theme {
  --color-beyond-the-pines: #637f3f;
  --color-beyond-the-pines-50: #ecfbdf;
  --color-beyond-the-pines-100: #ddefce;
  --color-beyond-the-pines-200: #c6ddb2;
  --color-beyond-the-pines-300: #a7c28e;
  --color-beyond-the-pines-400: #8daa6c;
  --color-beyond-the-pines-500: #73924a;
  --color-beyond-the-pines-600: #617c40;
  --color-beyond-the-pines-700: #4e6333;
  --color-beyond-the-pines-800: #3a4822;
  --color-beyond-the-pines-900: #273217;
  --color-beyond-the-pines-950: #161e08;
}

SCSS

$beyond-the-pines: #637f3f;
$beyond-the-pines-rgb: 99, 127, 63;
$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);
}