#A0C4FF

CSS

:root {
  --pastel-blue: #a0c4ff;
  --pastel-blue-rgb: 160 196 255;
  --pastel-blue-oklch: oklch(0.816 0.092 260.1);
}

.element {
  color: var(--pastel-blue);
  background-color: hsl(217 100% 81%);
  border-color: oklch(0.816 0.092 260.1);
}

Tailwind CSS v4

@theme {
  --color-pastel-blue: #a0c4ff;
  --color-pastel-blue-50: #e7f6ff;
  --color-pastel-blue-100: #d7e9ff;
  --color-pastel-blue-200: #bfd5fd;
  --color-pastel-blue-300: #9eb8e7;
  --color-pastel-blue-400: #7f9fd5;
  --color-pastel-blue-500: #6286c3;
  --color-pastel-blue-600: #5372a5;
  --color-pastel-blue-700: #425b84;
  --color-pastel-blue-800: #2e4362;
  --color-pastel-blue-900: #1f2e45;
  --color-pastel-blue-950: #0f1b2d;
}

SCSS

$pastel-blue: #a0c4ff;
$pastel-blue-rgb: 160, 196, 255;
$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);
}