#19142A

CSS

:root {
  --dark-knight: #19142a;
  --dark-knight-rgb: 25 20 42;
  --dark-knight-oklch: oklch(0.21 0.043 292.8);
}

.element {
  color: var(--dark-knight);
  background-color: hsl(254 35% 12%);
  border-color: oklch(0.21 0.043 292.8);
}

Tailwind CSS v4

@theme {
  --color-dark-knight: #19142a;
  --color-dark-knight-50: #f6f3ff;
  --color-dark-knight-100: #e8e5f5;
  --color-dark-knight-200: #d5d1e5;
  --color-dark-knight-300: #b8b4cc;
  --color-dark-knight-400: #9f9ab6;
  --color-dark-knight-500: #8781a1;
  --color-dark-knight-600: #726d88;
  --color-dark-knight-700: #5b586d;
  --color-dark-knight-800: #424050;
  --color-dark-knight-900: #2e2c38;
  --color-dark-knight-950: #1a1923;
}

SCSS

$dark-knight: #19142a;
$dark-knight-rgb: 25, 20, 42;
$dark-knight-light: mix(#fff, $dark-knight, 20%);
$dark-knight-dark: mix(#000, $dark-knight, 20%);

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