#645AD9

CSS

:root {
  --warm-blue: #645ad9;
  --warm-blue-rgb: 100 90 217;
  --warm-blue-oklch: oklch(0.547 0.188 281.8);
}

.element {
  color: var(--warm-blue);
  background-color: hsl(245 63% 60%);
  border-color: oklch(0.547 0.188 281.8);
}

Tailwind CSS v4

@theme {
  --color-warm-blue: #645ad9;
  --color-warm-blue-50: #eeefff;
  --color-warm-blue-100: #dfe0ff;
  --color-warm-blue-200: #cac9ff;
  --color-warm-blue-300: #aca9ff;
  --color-warm-blue-400: #8f8cff;
  --color-warm-blue-500: #776dfc;
  --color-warm-blue-600: #655dd5;
  --color-warm-blue-700: #504aab;
  --color-warm-blue-800: #383681;
  --color-warm-blue-900: #26255b;
  --color-warm-blue-950: #15133e;
}

SCSS

$warm-blue: #645ad9;
$warm-blue-rgb: 100, 90, 217;
$warm-blue-light: mix(#fff, $warm-blue, 20%);
$warm-blue-dark: mix(#000, $warm-blue, 20%);

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