#27739A

CSS

:root {
  --chill-of-the-night: #27739a;
  --chill-of-the-night-rgb: 39 115 154;
  --chill-of-the-night-oklch: oklch(0.527 0.095 235.3);
}

.element {
  color: var(--chill-of-the-night);
  background-color: hsl(200 60% 38%);
  border-color: oklch(0.527 0.095 235.3);
}

Tailwind CSS v4

@theme {
  --color-chill-of-the-night: #27739a;
  --color-chill-of-the-night-50: #ddfaff;
  --color-chill-of-the-night-100: #cbedff;
  --color-chill-of-the-night-200: #afdbf8;
  --color-chill-of-the-night-300: #89bfe2;
  --color-chill-of-the-night-400: #63a7cf;
  --color-chill-of-the-night-500: #3c90bc;
  --color-chill-of-the-night-600: #34799f;
  --color-chill-of-the-night-700: #2a617f;
  --color-chill-of-the-night-800: #1b485e;
  --color-chill-of-the-night-900: #113242;
  --color-chill-of-the-night-950: #041d2a;
}

SCSS

$chill-of-the-night: #27739a;
$chill-of-the-night-rgb: 39, 115, 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);
}