#636DC4

CSS

:root {
  --loch-ness: #636dc4;
  --loch-ness-rgb: 99 109 196;
  --loch-ness-oklch: oklch(0.568 0.134 276.3);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(234 45% 58%);
  border-color: oklch(0.568 0.134 276.3);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #636dc4;
  --color-loch-ness-50: #ecf2ff;
  --color-loch-ness-100: #dde4ff;
  --color-loch-ness-200: #c7cfff;
  --color-loch-ness-300: #a8b1fb;
  --color-loch-ness-400: #8a96ed;
  --color-loch-ness-500: #707bdd;
  --color-loch-ness-600: #5f69ba;
  --color-loch-ness-700: #4c5496;
  --color-loch-ness-800: #353d70;
  --color-loch-ness-900: #242a4f;
  --color-loch-ness-950: #131735;
}

SCSS

$loch-ness: #636dc4;
$loch-ness-rgb: 99, 109, 196;
$loch-ness-light: mix(#fff, $loch-ness, 20%);
$loch-ness-dark: mix(#000, $loch-ness, 20%);

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