Dark

CSS

:root {
  --dark: #1b2431;
  --dark-rgb: 27 36 49;
  --dark-oklch: oklch(0.258 0.028 257.5);
}

.element {
  color: var(--dark);
  background-color: hsl(215 29% 15%);
  border-color: oklch(0.258 0.028 257.5);
}

Tailwind CSS v4

@theme {
  --color-dark: #1b2431;
  --color-dark-50: #f0f5fd;
  --color-dark-100: #e2e8f1;
  --color-dark-200: #cdd5e0;
  --color-dark-300: #afb8c6;
  --color-dark-400: #949faf;
  --color-dark-500: #7b8799;
  --color-dark-600: #687281;
  --color-dark-700: #535b68;
  --color-dark-800: #3c434c;
  --color-dark-900: #292e35;
  --color-dark-950: #171b20;
}

SCSS

$dark: #1b2431;
$dark-rgb: 27, 36, 49;
$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);
}