River Styx

CSS

:root {
  --river-styx: #161820;
  --river-styx-rgb: 22 24 32;
  --river-styx-oklch: oklch(0.211 0.016 274);
}

.element {
  color: var(--river-styx);
  background-color: hsl(228 19% 11%);
  border-color: oklch(0.211 0.016 274);
}

Tailwind CSS v4

@theme {
  --color-river-styx: #161820;
  --color-river-styx-50: #f4f5fa;
  --color-river-styx-100: #e6e7ed;
  --color-river-styx-200: #d2d4db;
  --color-river-styx-300: #b5b7c0;
  --color-river-styx-400: #9b9ea8;
  --color-river-styx-500: #838691;
  --color-river-styx-600: #6f717b;
  --color-river-styx-700: #585a62;
  --color-river-styx-800: #404248;
  --color-river-styx-900: #2c2e32;
  --color-river-styx-950: #191a1e;
}

SCSS

$river-styx: #161820;
$river-styx-rgb: 22, 24, 32;
$river-styx-light: mix(#fff, $river-styx, 20%);
$river-styx-dark: mix(#000, $river-styx, 20%);

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