#00657B

CSS

:root {
  --teal-with-it: #00657b;
  --teal-with-it-rgb: 0 101 123;
  --teal-with-it-oklch: oklch(0.469 0.085 219.6);
}

.element {
  color: var(--teal-with-it);
  background-color: hsl(191 100% 24%);
  border-color: oklch(0.469 0.085 219.6);
}

Tailwind CSS v4

@theme {
  --color-teal-with-it: #00657b;
  --color-teal-with-it-50: #dcfbff;
  --color-teal-with-it-100: #caeffc;
  --color-teal-with-it-200: #adddee;
  --color-teal-with-it-300: #86c2d7;
  --color-teal-with-it-400: #60abc1;
  --color-teal-with-it-500: #3693ad;
  --color-teal-with-it-600: #307d92;
  --color-teal-with-it-700: #266475;
  --color-teal-with-it-800: #194956;
  --color-teal-with-it-900: #10333c;
  --color-teal-with-it-950: #031f26;
}

SCSS

$teal-with-it: #00657b;
$teal-with-it-rgb: 0, 101, 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);
}