#566AA5

CSS

:root {
  --loch-ness: #566aa5;
  --loch-ness-rgb: 86 106 165;
  --loch-ness-oklch: oklch(0.535 0.096 268.8);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(225 31% 49%);
  border-color: oklch(0.535 0.096 268.8);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #566aa5;
  --color-loch-ness-50: #ebf4ff;
  --color-loch-ness-100: #dce7ff;
  --color-loch-ness-200: #c5d3fe;
  --color-loch-ness-300: #a5b5e9;
  --color-loch-ness-400: #879cd8;
  --color-loch-ness-500: #6c83c6;
  --color-loch-ness-600: #5b6fa7;
  --color-loch-ness-700: #495986;
  --color-loch-ness-800: #334164;
  --color-loch-ness-900: #232d46;
  --color-loch-ness-950: #121a2e;
}

SCSS

$loch-ness: #566aa5;
$loch-ness-rgb: 86, 106, 165;
$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);
}