#E4F0F6

CSS

:root {
  --out-cold: #e4f0f6;
  --out-cold-rgb: 228 240 246;
  --out-cold-oklch: oklch(0.948 0.015 229);
}

.element {
  color: var(--out-cold);
  background-color: hsl(200 50% 93%);
  border-color: oklch(0.948 0.015 229);
}

Tailwind CSS v4

@theme {
  --color-out-cold: #e4f0f6;
  --color-out-cold-50: #f1f6f9;
  --color-out-cold-100: #e3e9ec;
  --color-out-cold-200: #ced5da;
  --color-out-cold-300: #b0b9be;
  --color-out-cold-400: #96a0a6;
  --color-out-cold-500: #7c888e;
  --color-out-cold-600: #697378;
  --color-out-cold-700: #545c60;
  --color-out-cold-800: #3d4446;
  --color-out-cold-900: #2a2f31;
  --color-out-cold-950: #181b1d;
}

SCSS

$out-cold: #e4f0f6;
$out-cold-rgb: 228, 240, 246;
$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);
}