Dark River

CSS

:root {
  --dark-river: #3e4445;
  --dark-river-rgb: 62 68 69;
  --dark-river-oklch: oklch(0.381 0.008 208.8);
}

.element {
  color: var(--dark-river);
  background-color: hsl(189 5% 26%);
  border-color: oklch(0.381 0.008 208.8);
}

Tailwind CSS v4

@theme {
  --color-dark-river: #3e4445;
  --color-dark-river-50: #f3f6f6;
  --color-dark-river-100: #e5e9e9;
  --color-dark-river-200: #d0d5d6;
  --color-dark-river-300: #b3b8ba;
  --color-dark-river-400: #99a0a1;
  --color-dark-river-500: #808889;
  --color-dark-river-600: #6d7374;
  --color-dark-river-700: #575c5d;
  --color-dark-river-800: #3f4344;
  --color-dark-river-900: #2c2e2f;
  --color-dark-river-950: #191b1b;
}

SCSS

$dark-river: #3e4445;
$dark-river-rgb: 62, 68, 69;
$dark-river-light: mix(#fff, $dark-river, 20%);
$dark-river-dark: mix(#000, $dark-river, 20%);

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