#537C74

CSS

:root {
  --turquoise-tortoise: #537c74;
  --turquoise-tortoise-rgb: 83 124 116;
  --turquoise-tortoise-oklch: oklch(0.554 0.047 180.9);
}

.element {
  color: var(--turquoise-tortoise);
  background-color: hsl(168 20% 41%);
  border-color: oklch(0.554 0.047 180.9);
}

Tailwind CSS v4

@theme {
  --color-turquoise-tortoise: #537c74;
  --color-turquoise-tortoise-50: #e7faf6;
  --color-turquoise-tortoise-100: #d8ede9;
  --color-turquoise-tortoise-200: #bfdbd6;
  --color-turquoise-tortoise-300: #9dc0b9;
  --color-turquoise-tortoise-400: #80a8a0;
  --color-turquoise-tortoise-500: #639188;
  --color-turquoise-tortoise-600: #547b73;
  --color-turquoise-tortoise-700: #43625c;
  --color-turquoise-tortoise-800: #304843;
  --color-turquoise-tortoise-900: #21322e;
  --color-turquoise-tortoise-950: #101e1b;
}

SCSS

$turquoise-tortoise: #537c74;
$turquoise-tortoise-rgb: 83, 124, 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);
}