#161F2A

CSS

:root {
  --dark: #161f2a;
  --dark-rgb: 22 31 42;
  --dark-oklch: oklch(0.236 0.025 253.8);
}

.element {
  color: var(--dark);
  background-color: hsl(213 31% 13%);
  border-color: oklch(0.236 0.025 253.8);
}

Tailwind CSS v4

@theme {
  --color-dark: #161f2a;
  --color-dark-50: #f1f6fc;
  --color-dark-100: #e2e8f0;
  --color-dark-200: #cdd5df;
  --color-dark-300: #afb8c4;
  --color-dark-400: #95a0ad;
  --color-dark-500: #7b8797;
  --color-dark-600: #687380;
  --color-dark-700: #535c66;
  --color-dark-800: #3c434b;
  --color-dark-900: #292e34;
  --color-dark-950: #171b1f;
}

SCSS

$dark: #161f2a;
$dark-rgb: 22, 31, 42;
$dark-light: mix(#fff, $dark, 20%);
$dark-dark: mix(#000, $dark, 20%);

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