Shadow of Night

CSS

:root {
  --shadow-of-night: #2a4f61;
  --shadow-of-night-rgb: 42 79 97;
  --shadow-of-night-oklch: oklch(0.408 0.052 231);
}

.element {
  color: var(--shadow-of-night);
  background-color: hsl(200 40% 27%);
  border-color: oklch(0.408 0.052 231);
}

Tailwind CSS v4

@theme {
  --color-shadow-of-night: #2a4f61;
  --color-shadow-of-night-50: #e7f8ff;
  --color-shadow-of-night-100: #d8ebf7;
  --color-shadow-of-night-200: #bfd9e7;
  --color-shadow-of-night-300: #9ebdce;
  --color-shadow-of-night-400: #7fa5b8;
  --color-shadow-of-night-500: #628da3;
  --color-shadow-of-night-600: #537789;
  --color-shadow-of-night-700: #435f6e;
  --color-shadow-of-night-800: #2f4651;
  --color-shadow-of-night-900: #203038;
  --color-shadow-of-night-950: #0f1d23;
}

SCSS

$shadow-of-night: #2a4f61;
$shadow-of-night-rgb: 42, 79, 97;
$shadow-of-night-light: mix(#fff, $shadow-of-night, 20%);
$shadow-of-night-dark: mix(#000, $shadow-of-night, 20%);

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