#141A2C

CSS

:root {
  --sombre-night: #141a2c;
  --sombre-night-rgb: 20 26 44;
  --sombre-night-oklch: oklch(0.221 0.037 269.2);
}

.element {
  color: var(--sombre-night);
  background-color: hsl(225 38% 13%);
  border-color: oklch(0.221 0.037 269.2);
}

Tailwind CSS v4

@theme {
  --color-sombre-night: #141a2c;
  --color-sombre-night-50: #f1f5ff;
  --color-sombre-night-100: #e3e7f5;
  --color-sombre-night-200: #ced4e4;
  --color-sombre-night-300: #b0b7cb;
  --color-sombre-night-400: #959eb5;
  --color-sombre-night-500: #7c869f;
  --color-sombre-night-600: #697186;
  --color-sombre-night-700: #545a6c;
  --color-sombre-night-800: #3d424f;
  --color-sombre-night-900: #2a2e37;
  --color-sombre-night-950: #171a22;
}

SCSS

$sombre-night: #141a2c;
$sombre-night-rgb: 20, 26, 44;
$sombre-night-light: mix(#fff, $sombre-night, 20%);
$sombre-night-dark: mix(#000, $sombre-night, 20%);

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