#3B817C

CSS

:root {
  --turquoise-tortoise: #3b817c;
  --turquoise-tortoise-rgb: 59 129 124;
  --turquoise-tortoise-oklch: oklch(0.557 0.071 189.1);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(176 37% 37%);
  border-color: oklch(0.557 0.071 189.1);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #3b817c;
  --color-turquoise-tortoise-50: #dffcfa;
  --color-turquoise-tortoise-100: #cef0ed;
  --color-turquoise-tortoise-200: #b2dedb;
  --color-turquoise-tortoise-300: #8dc3c0;
  --color-turquoise-tortoise-400: #6baca7;
  --color-turquoise-tortoise-500: #479590;
  --color-turquoise-tortoise-600: #3d7e7a;
  --color-turquoise-tortoise-700: #316561;
  --color-turquoise-tortoise-800: #224a46;
  --color-turquoise-tortoise-900: #173431;
  --color-turquoise-tortoise-950: #071f1d;
}

SCSS

$turquoise-tortoise: #3b817c;
$turquoise-tortoise-rgb: 59, 129, 124;
$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);
}