#517C78

CSS

:root {
  --turquoise-tortoise: #517c78;
  --turquoise-tortoise-rgb: 81 124 120;
  --turquoise-tortoise-oklch: oklch(0.554 0.048 188.5);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(174 21% 40%);
  border-color: oklch(0.554 0.048 188.5);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #517c78;
  --color-turquoise-tortoise-50: #e6faf8;
  --color-turquoise-tortoise-100: #d7edeb;
  --color-turquoise-tortoise-200: #bedbd9;
  --color-turquoise-tortoise-300: #9cc0bd;
  --color-turquoise-tortoise-400: #7ea8a4;
  --color-turquoise-tortoise-500: #60918c;
  --color-turquoise-tortoise-600: #527a77;
  --color-turquoise-tortoise-700: #41625f;
  --color-turquoise-tortoise-800: #2f4845;
  --color-turquoise-tortoise-900: #203230;
  --color-turquoise-tortoise-950: #0f1e1c;
}

SCSS

$turquoise-tortoise: #517c78;
$turquoise-tortoise-rgb: 81, 124, 120;
$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);
}