#066FEF

CSS

:root {
  --deep-sky-blue: #066fef;
  --deep-sky-blue-rgb: 6 111 239;
  --deep-sky-blue-oklch: oklch(0.568 0.21 258.3);
}

.element {
  color: var(--deep-sky-blue);
  background-color: hsl(213 95% 48%);
  border-color: oklch(0.568 0.21 258.3);
}

Tailwind CSS v4

@theme {
  --color-deep-sky-blue: #066fef;
  --color-deep-sky-blue-50: #d3f7ff;
  --color-deep-sky-blue-100: #bfe9ff;
  --color-deep-sky-blue-200: #9fd5ff;
  --color-deep-sky-blue-300: #76b6ff;
  --color-deep-sky-blue-400: #469bff;
  --color-deep-sky-blue-500: #037dff;
  --color-deep-sky-blue-600: #0c6ae3;
  --color-deep-sky-blue-700: #0b55b6;
  --color-deep-sky-blue-800: #003f89;
  --color-deep-sky-blue-900: #002c61;
  --color-deep-sky-blue-950: #001842;
}

SCSS

$deep-sky-blue: #066fef;
$deep-sky-blue-rgb: 6, 111, 239;
$deep-sky-blue-light: mix(#fff, $deep-sky-blue, 20%);
$deep-sky-blue-dark: mix(#000, $deep-sky-blue, 20%);

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