#00687B

CSS

:root {
  --teal-with-it: #00687b;
  --teal-with-it-rgb: 0 104 123;
  --teal-with-it-oklch: oklch(0.477 0.085 216.1);
}

.element {
  color: var(--teal-with-it);
  background-color: hsl(189 100% 24%);
  border-color: oklch(0.477 0.085 216.1);
}

Tailwind CSS v4

@theme {
  --color-teal-with-it: #00687b;
  --color-teal-with-it-50: #dbfcff;
  --color-teal-with-it-100: #c9effb;
  --color-teal-with-it-200: #acdeed;
  --color-teal-with-it-300: #85c2d4;
  --color-teal-with-it-400: #5fabbe;
  --color-teal-with-it-500: #3494aa;
  --color-teal-with-it-600: #2e7d90;
  --color-teal-with-it-700: #256473;
  --color-teal-with-it-800: #184a54;
  --color-teal-with-it-900: #10333b;
  --color-teal-with-it-950: #021f25;
}

SCSS

$teal-with-it: #00687b;
$teal-with-it-rgb: 0, 104, 123;
$teal-with-it-light: mix(#fff, $teal-with-it, 20%);
$teal-with-it-dark: mix(#000, $teal-with-it, 20%);

.element {
  color: $teal-with-it;
  box-shadow: 0 0 0 2px rgba($teal-with-it, 0.35);
}