#E9F2F9

CSS

:root {
  --out-cold: #e9f2f9;
  --out-cold-rgb: 233 242 249;
  --out-cold-oklch: oklch(0.956 0.013 241);
}

.element {
  color: var(--out-cold);
  background-color: hsl(206 57% 95%);
  border-color: oklch(0.956 0.013 241);
}

Tailwind CSS v4

@theme {
  --color-out-cold: #e9f2f9;
  --color-out-cold-50: #f2f6f9;
  --color-out-cold-100: #e4e8ec;
  --color-out-cold-200: #cfd5da;
  --color-out-cold-300: #b2b8be;
  --color-out-cold-400: #98a0a6;
  --color-out-cold-500: #7f888e;
  --color-out-cold-600: #6b7378;
  --color-out-cold-700: #565c60;
  --color-out-cold-800: #3e4347;
  --color-out-cold-900: #2b2e31;
  --color-out-cold-950: #181b1d;
}

SCSS

$out-cold: #e9f2f9;
$out-cold-rgb: 233, 242, 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);
}