#6EA1C1

CSS

:root {
  --wandering-river: #6ea1c1;
  --wandering-river-rgb: 110 161 193;
  --wandering-river-oklch: oklch(0.685 0.072 236.8);
}

.element {
  color: var(--wandering-river);
  background-color: hsl(203 40% 59%);
  border-color: oklch(0.685 0.072 236.8);
}

Tailwind CSS v4

@theme {
  --color-wandering-river: #6ea1c1;
  --color-wandering-river-50: #e3f9ff;
  --color-wandering-river-100: #d3ecfe;
  --color-wandering-river-200: #b9d9f0;
  --color-wandering-river-300: #96bdd9;
  --color-wandering-river-400: #75a5c4;
  --color-wandering-river-500: #558eb0;
  --color-wandering-river-600: #497895;
  --color-wandering-river-700: #3a6077;
  --color-wandering-river-800: #284658;
  --color-wandering-river-900: #1b313d;
  --color-wandering-river-950: #0b1d27;
}

SCSS

$wandering-river: #6ea1c1;
$wandering-river-rgb: 110, 161, 193;
$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);
}