#6FA1BF

CSS

:root {
  --wandering-river: #6fa1bf;
  --wandering-river-rgb: 111 161 191;
  --wandering-river-oklch: oklch(0.685 0.069 235.5);
}

.element {
  color: var(--wandering-river);
  background-color: hsl(203 38% 59%);
  border-color: oklch(0.685 0.069 235.5);
}

Tailwind CSS v4

@theme {
  --color-wandering-river: #6fa1bf;
  --color-wandering-river-50: #e4f9ff;
  --color-wandering-river-100: #d3ecfd;
  --color-wandering-river-200: #b9d9ef;
  --color-wandering-river-300: #97bdd7;
  --color-wandering-river-400: #76a5c2;
  --color-wandering-river-500: #568eae;
  --color-wandering-river-600: #4a7893;
  --color-wandering-river-700: #3b6076;
  --color-wandering-river-800: #294757;
  --color-wandering-river-900: #1b313d;
  --color-wandering-river-950: #0b1d26;
}

SCSS

$wandering-river: #6fa1bf;
$wandering-river-rgb: 111, 161, 191;
$wandering-river-light: mix(#fff, $wandering-river, 20%);
$wandering-river-dark: mix(#000, $wandering-river, 20%);

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