#517D74

CSS

:root {
  --turquoise-tortoise: #517d74;
  --turquoise-tortoise-rgb: 81 125 116;
  --turquoise-tortoise-oklch: oklch(0.555 0.051 180);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(168 21% 40%);
  border-color: oklch(0.555 0.051 180);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #517d74;
  --color-turquoise-tortoise-50: #e6faf6;
  --color-turquoise-tortoise-100: #d6eee9;
  --color-turquoise-tortoise-200: #bedcd6;
  --color-turquoise-tortoise-300: #9cc0b9;
  --color-turquoise-tortoise-400: #7ea99f;
  --color-turquoise-tortoise-500: #609287;
  --color-turquoise-tortoise-600: #527b73;
  --color-turquoise-tortoise-700: #41635c;
  --color-turquoise-tortoise-800: #2f4842;
  --color-turquoise-tortoise-900: #20322e;
  --color-turquoise-tortoise-950: #0f1e1b;
}

SCSS

$turquoise-tortoise: #517d74;
$turquoise-tortoise-rgb: 81, 125, 116;
$turquoise-tortoise-light: mix(#fff, $turquoise-tortoise, 20%);
$turquoise-tortoise-dark: mix(#000, $turquoise-tortoise, 20%);

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