#E4F1F9

CSS

:root {
  --out-cold: #e4f1f9;
  --out-cold-rgb: 228 241 249;
  --out-cold-oklch: oklch(0.951 0.018 234.5);
}

.element {
  color: var(--out-cold);
  background-color: hsl(203 64% 94%);
  border-color: oklch(0.951 0.018 234.5);
}

Tailwind CSS v4

@theme {
  --color-out-cold: #e4f1f9;
  --color-out-cold-50: #f1f6fa;
  --color-out-cold-100: #e3e9ed;
  --color-out-cold-200: #ced6db;
  --color-out-cold-300: #afb9bf;
  --color-out-cold-400: #95a0a7;
  --color-out-cold-500: #7b8890;
  --color-out-cold-600: #69737a;
  --color-out-cold-700: #535c62;
  --color-out-cold-800: #3d4447;
  --color-out-cold-900: #2a2f32;
  --color-out-cold-950: #171b1d;
}

SCSS

$out-cold: #e4f1f9;
$out-cold-rgb: 228, 241, 249;
$out-cold-light: mix(#fff, $out-cold, 20%);
$out-cold-dark: mix(#000, $out-cold, 20%);

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