#A6BFFD

CSS

:root {
  --pastel-blue: #a6bffd;
  --pastel-blue-rgb: 166 191 253;
  --pastel-blue-oklch: oklch(0.808 0.092 267.4);
}

.element {
  color: var(--pastel-blue);
  background-color: hsl(223 96% 82%);
  border-color: oklch(0.808 0.092 267.4);
}

Tailwind CSS v4

@theme {
  --color-pastel-blue: #a6bffd;
  --color-pastel-blue-50: #eaf5ff;
  --color-pastel-blue-100: #dbe7ff;
  --color-pastel-blue-200: #c4d3fd;
  --color-pastel-blue-300: #a4b6e8;
  --color-pastel-blue-400: #869dd6;
  --color-pastel-blue-500: #6b84c4;
  --color-pastel-blue-600: #5b70a5;
  --color-pastel-blue-700: #485985;
  --color-pastel-blue-800: #334263;
  --color-pastel-blue-900: #232d45;
  --color-pastel-blue-950: #121a2d;
}

SCSS

$pastel-blue: #a6bffd;
$pastel-blue-rgb: 166, 191, 253;
$pastel-blue-light: mix(#fff, $pastel-blue, 20%);
$pastel-blue-dark: mix(#000, $pastel-blue, 20%);

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