#78781F

CSS

:root {
  --olive: #78781f;
  --olive-rgb: 120 120 31;
  --olive-oklch: oklch(0.556 0.108 109.5);
}

.element {
  color: var(--olive);
  background-color: hsl(60 59% 30%);
  border-color: oklch(0.556 0.108 109.5);
}

Tailwind CSS v4

@theme {
  --color-olive: #78781f;
  --color-olive-50: #f6f9d6;
  --color-olive-100: #e8ecc3;
  --color-olive-200: #d5d9a4;
  --color-olive-300: #b9bd7c;
  --color-olive-400: #a3a455;
  --color-olive-500: #8c8c28;
  --color-olive-600: #767624;
  --color-olive-700: #5e5f1d;
  --color-olive-800: #464511;
  --color-olive-900: #31300b;
  --color-olive-950: #1d1c01;
}

SCSS

$olive: #78781f;
$olive-rgb: 120, 120, 31;
$olive-light: mix(#fff, $olive, 20%);
$olive-dark: mix(#000, $olive, 20%);

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