#5B6FC5

CSS

:root {
  --loch-ness: #5b6fc5;
  --loch-ness-rgb: 91 111 197;
  --loch-ness-oklch: oklch(0.567 0.134 271.7);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(229 48% 56%);
  border-color: oklch(0.567 0.134 271.7);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #5b6fc5;
  --color-loch-ness-50: #e8f3ff;
  --color-loch-ness-100: #d9e6ff;
  --color-loch-ness-200: #c2d1ff;
  --color-loch-ness-300: #a1b2fc;
  --color-loch-ness-400: #8299ee;
  --color-loch-ness-500: #677ede;
  --color-loch-ness-600: #586bbc;
  --color-loch-ness-700: #465597;
  --color-loch-ness-800: #303f71;
  --color-loch-ness-900: #212b4f;
  --color-loch-ness-950: #101835;
}

SCSS

$loch-ness: #5b6fc5;
$loch-ness-rgb: 91, 111, 197;
$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);
}