#2171EE

CSS

:root {
  --deep-sky-blue: #2171ee;
  --deep-sky-blue-rgb: 33 113 238;
  --deep-sky-blue-oklch: oklch(0.575 0.203 259.7);
}

.element {
  color: var(--deep-sky-blue);
  background-color: hsl(217 86% 53%);
  border-color: oklch(0.575 0.203 259.7);
}

Tailwind CSS v4

@theme {
  --color-deep-sky-blue: #2171ee;
  --color-deep-sky-blue-50: #d5f6ff;
  --color-deep-sky-blue-100: #c3e9ff;
  --color-deep-sky-blue-200: #a4d4ff;
  --color-deep-sky-blue-300: #7cb5ff;
  --color-deep-sky-blue-400: #509aff;
  --color-deep-sky-blue-500: #227dff;
  --color-deep-sky-blue-600: #1f6ae0;
  --color-deep-sky-blue-700: #1955b4;
  --color-deep-sky-blue-800: #063f87;
  --color-deep-sky-blue-900: #052b5f;
  --color-deep-sky-blue-950: #001841;
}

SCSS

$deep-sky-blue: #2171ee;
$deep-sky-blue-rgb: 33, 113, 238;
$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);
}