#F5F9FB

CSS

:root {
  --heart-of-ice: #f5f9fb;
  --heart-of-ice-rgb: 245 249 251;
  --heart-of-ice-oklch: oklch(0.98 0.005 228.8);
}

.element {
  color: var(--heart-of-ice);
  background-color: hsl(200 43% 97%);
  border-color: oklch(0.98 0.005 228.8);
}

Tailwind CSS v4

@theme {
  --color-heart-of-ice: #f5f9fb;
  --color-heart-of-ice-50: #f4f5f6;
  --color-heart-of-ice-100: #e6e8e9;
  --color-heart-of-ice-200: #d2d5d6;
  --color-heart-of-ice-300: #b5b8b9;
  --color-heart-of-ice-400: #9b9fa1;
  --color-heart-of-ice-500: #838789;
  --color-heart-of-ice-600: #6f7274;
  --color-heart-of-ice-700: #595b5d;
  --color-heart-of-ice-800: #414344;
  --color-heart-of-ice-900: #2c2e2f;
  --color-heart-of-ice-950: #1a1b1b;
}

SCSS

$heart-of-ice: #f5f9fb;
$heart-of-ice-rgb: 245, 249, 251;
$heart-of-ice-light: mix(#fff, $heart-of-ice, 20%);
$heart-of-ice-dark: mix(#000, $heart-of-ice, 20%);

.element {
  color: $heart-of-ice;
  box-shadow: 0 0 0 2px rgba($heart-of-ice, 0.35);
}