#26282F

CSS

:root {
  --night-sky: #26282f;
  --night-sky-rgb: 38 40 47;
  --night-sky-oklch: oklch(0.278 0.013 272.9);
}

.element {
  color: var(--night-sky);
  background-color: hsl(227 11% 17%);
  border-color: oklch(0.278 0.013 272.9);
}

Tailwind CSS v4

@theme {
  --color-night-sky: #26282f;
  --color-night-sky-50: #f4f5f9;
  --color-night-sky-100: #e6e8ec;
  --color-night-sky-200: #d2d4da;
  --color-night-sky-300: #b5b7be;
  --color-night-sky-400: #9c9ea6;
  --color-night-sky-500: #83868f;
  --color-night-sky-600: #6f7179;
  --color-night-sky-700: #595b61;
  --color-night-sky-800: #414247;
  --color-night-sky-900: #2c2e31;
  --color-night-sky-950: #1a1a1d;
}

SCSS

$night-sky: #26282f;
$night-sky-rgb: 38, 40, 47;
$night-sky-light: mix(#fff, $night-sky, 20%);
$night-sky-dark: mix(#000, $night-sky, 20%);

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