#2A3F4A

CSS

:root {
  --depths-of-the-nile: #2a3f4a;
  --depths-of-the-nile-rgb: 42 63 74;
  --depths-of-the-nile-oklch: oklch(0.355 0.033 231.7);
}

.element {
  color: var(--depths-of-the-nile);
  background-color: hsl(201 28% 23%);
  border-color: oklch(0.355 0.033 231.7);
}

Tailwind CSS v4

@theme {
  --color-depths-of-the-nile: #2a3f4a;
  --color-depths-of-the-nile-50: #edf7fd;
  --color-depths-of-the-nile-100: #deeaf1;
  --color-depths-of-the-nile-200: #c7d7e0;
  --color-depths-of-the-nile-300: #a8bbc6;
  --color-depths-of-the-nile-400: #8ca2af;
  --color-depths-of-the-nile-500: #718a98;
  --color-depths-of-the-nile-600: #607581;
  --color-depths-of-the-nile-700: #4c5e67;
  --color-depths-of-the-nile-800: #37454c;
  --color-depths-of-the-nile-900: #263034;
  --color-depths-of-the-nile-950: #141c20;
}

SCSS

$depths-of-the-nile: #2a3f4a;
$depths-of-the-nile-rgb: 42, 63, 74;
$depths-of-the-nile-light: mix(#fff, $depths-of-the-nile, 20%);
$depths-of-the-nile-dark: mix(#000, $depths-of-the-nile, 20%);

.element {
  color: $depths-of-the-nile;
  box-shadow: 0 0 0 2px rgba($depths-of-the-nile, 0.35);
}