#00729A

CSS

:root {
  --chill-of-the-night: #00729a;
  --chill-of-the-night-rgb: 0 114 154;
  --chill-of-the-night-oklch: oklch(0.518 0.105 231.7);
}

.element {
  color: var(--chill-of-the-night);
  background-color: hsl(196 100% 30%);
  border-color: oklch(0.518 0.105 231.7);
}

Tailwind CSS v4

@theme {
  --color-chill-of-the-night: #00729a;
  --color-chill-of-the-night-50: #d9fbff;
  --color-chill-of-the-night-100: #c6efff;
  --color-chill-of-the-night-200: #a8ddfb;
  --color-chill-of-the-night-300: #80c1e5;
  --color-chill-of-the-night-400: #56a9d2;
  --color-chill-of-the-night-500: #2392bf;
  --color-chill-of-the-night-600: #227ba2;
  --color-chill-of-the-night-700: #1b6382;
  --color-chill-of-the-night-800: #0f4960;
  --color-chill-of-the-night-900: #093243;
  --color-chill-of-the-night-950: #001e2b;
}

SCSS

$chill-of-the-night: #00729a;
$chill-of-the-night-rgb: 0, 114, 154;
$chill-of-the-night-light: mix(#fff, $chill-of-the-night, 20%);
$chill-of-the-night-dark: mix(#000, $chill-of-the-night, 20%);

.element {
  color: $chill-of-the-night;
  box-shadow: 0 0 0 2px rgba($chill-of-the-night, 0.35);
}