#266FE7

CSS

:root {
  --deep-sky-blue: #266fe7;
  --deep-sky-blue-rgb: 38 111 231;
  --deep-sky-blue-oklch: oklch(0.567 0.196 260.1);
}

.element {
  color: var(--deep-sky-blue);
  background-color: hsl(217 80% 53%);
  border-color: oklch(0.567 0.196 260.1);
}

Tailwind CSS v4

@theme {
  --color-deep-sky-blue: #266fe7;
  --color-deep-sky-blue-50: #d7f6ff;
  --color-deep-sky-blue-100: #c5e9ff;
  --color-deep-sky-blue-200: #a6d4ff;
  --color-deep-sky-blue-300: #7fb5ff;
  --color-deep-sky-blue-400: #559bff;
  --color-deep-sky-blue-500: #2b7eff;
  --color-deep-sky-blue-600: #266bdc;
  --color-deep-sky-blue-700: #1e56b1;
  --color-deep-sky-blue-800: #0d3f84;
  --color-deep-sky-blue-900: #082c5e;
  --color-deep-sky-blue-950: #001840;
}

SCSS

$deep-sky-blue: #266fe7;
$deep-sky-blue-rgb: 38, 111, 231;
$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);
}