#D9E4E4

CSS

:root {
  --smoke-and-mirrors: #d9e4e4;
  --smoke-and-mirrors-rgb: 217 228 228;
  --smoke-and-mirrors-oklch: oklch(0.911 0.012 196.9);
}

.element {
  color: var(--smoke-and-mirrors);
  background-color: hsl(180 17% 87%);
  border-color: oklch(0.911 0.012 196.9);
}

Tailwind CSS v4

@theme {
  --color-smoke-and-mirrors: #d9e4e4;
  --color-smoke-and-mirrors-50: #f1f6f6;
  --color-smoke-and-mirrors-100: #e4e9e9;
  --color-smoke-and-mirrors-200: #cfd6d6;
  --color-smoke-and-mirrors-300: #b1b9b9;
  --color-smoke-and-mirrors-400: #97a1a1;
  --color-smoke-and-mirrors-500: #7e8989;
  --color-smoke-and-mirrors-600: #6a7474;
  --color-smoke-and-mirrors-700: #555d5d;
  --color-smoke-and-mirrors-800: #3e4444;
  --color-smoke-and-mirrors-900: #2b2f2f;
  --color-smoke-and-mirrors-950: #181b1b;
}

SCSS

$smoke-and-mirrors: #d9e4e4;
$smoke-and-mirrors-rgb: 217, 228, 228;
$smoke-and-mirrors-light: mix(#fff, $smoke-and-mirrors, 20%);
$smoke-and-mirrors-dark: mix(#000, $smoke-and-mirrors, 20%);

.element {
  color: $smoke-and-mirrors;
  box-shadow: 0 0 0 2px rgba($smoke-and-mirrors, 0.35);
}