#2A7394

CSS

:root {
  --chill-of-the-night: #2a7394;
  --chill-of-the-night-rgb: 42 115 148;
  --chill-of-the-night-oklch: oklch(0.525 0.088 231.5);
}

.element {
  color: var(--chill-of-the-night);
  background-color: hsl(199 56% 37%);
  border-color: oklch(0.525 0.088 231.5);
}

Tailwind CSS v4

@theme {
  --color-chill-of-the-night: #2a7394;
  --color-chill-of-the-night-50: #defaff;
  --color-chill-of-the-night-100: #cceeff;
  --color-chill-of-the-night-200: #b0dbf4;
  --color-chill-of-the-night-300: #8ac0de;
  --color-chill-of-the-night-400: #66a8c9;
  --color-chill-of-the-night-500: #4090b6;
  --color-chill-of-the-night-600: #377a9a;
  --color-chill-of-the-night-700: #2c627b;
  --color-chill-of-the-night-800: #1d485b;
  --color-chill-of-the-night-900: #13323f;
  --color-chill-of-the-night-950: #051e28;
}

SCSS

$chill-of-the-night: #2a7394;
$chill-of-the-night-rgb: 42, 115, 148;
$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);
}