#537D6C

CSS

:root {
  --turquoise-tortoise: #537d6c;
  --turquoise-tortoise-rgb: 83 125 108;
  --turquoise-tortoise-oklch: oklch(0.554 0.054 167.2);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(156 20% 41%);
  border-color: oklch(0.554 0.054 167.2);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #537d6c;
  --color-turquoise-tortoise-50: #e7faf2;
  --color-turquoise-tortoise-100: #d7eee5;
  --color-turquoise-tortoise-200: #bfdcd0;
  --color-turquoise-tortoise-300: #9dc1b3;
  --color-turquoise-tortoise-400: #80a998;
  --color-turquoise-tortoise-500: #63927f;
  --color-turquoise-tortoise-600: #547b6b;
  --color-turquoise-tortoise-700: #436356;
  --color-turquoise-tortoise-800: #30483e;
  --color-turquoise-tortoise-900: #21322a;
  --color-turquoise-tortoise-950: #101e18;
}

SCSS

$turquoise-tortoise: #537d6c;
$turquoise-tortoise-rgb: 83, 125, 108;
$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);
}