#006574

CSS

:root {
  --teal-with-it: #006574;
  --teal-with-it-rgb: 0 101 116;
  --teal-with-it-oklch: oklch(0.465 0.081 212.3);
}

.element {
  color: var(--teal-with-it);
  background-color: hsl(188 100% 23%);
  border-color: oklch(0.465 0.081 212.3);
}

Tailwind CSS v4

@theme {
  --color-teal-with-it: #006574;
  --color-teal-with-it-50: #dcfcff;
  --color-teal-with-it-100: #caf0f9;
  --color-teal-with-it-200: #addeea;
  --color-teal-with-it-300: #86c3d1;
  --color-teal-with-it-400: #61abbb;
  --color-teal-with-it-500: #3794a6;
  --color-teal-with-it-600: #317d8c;
  --color-teal-with-it-700: #276470;
  --color-teal-with-it-800: #1a4a52;
  --color-teal-with-it-900: #113339;
  --color-teal-with-it-950: #031f23;
}

SCSS

$teal-with-it: #006574;
$teal-with-it-rgb: 0, 101, 116;
$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);
}