#1D2431

CSS

:root {
  --dark: #1d2431;
  --dark-rgb: 29 36 49;
  --dark-oklch: oklch(0.26 0.027 262.6);
}

.element {
  color: var(--dark);
  background-color: hsl(219 26% 15%);
  border-color: oklch(0.26 0.027 262.6);
}

Tailwind CSS v4

@theme {
  --color-dark: #1d2431;
  --color-dark-50: #f1f5fd;
  --color-dark-100: #e3e8f1;
  --color-dark-200: #cfd4e0;
  --color-dark-300: #b1b8c5;
  --color-dark-400: #969faf;
  --color-dark-500: #7d8798;
  --color-dark-600: #6a7281;
  --color-dark-700: #545b67;
  --color-dark-800: #3d434c;
  --color-dark-900: #2a2e35;
  --color-dark-950: #181b20;
}

SCSS

$dark: #1d2431;
$dark-rgb: 29, 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);
}