#5B71BC

CSS

:root {
  --loch-ness: #5b71bc;
  --loch-ness-rgb: 91 113 188;
  --loch-ness-oklch: oklch(0.566 0.119 269.9);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(226 42% 55%);
  border-color: oklch(0.566 0.119 269.9);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #5b71bc;
  --color-loch-ness-50: #e9f4ff;
  --color-loch-ness-100: #dae6ff;
  --color-loch-ness-200: #c2d2ff;
  --color-loch-ness-300: #a2b4f5;
  --color-loch-ness-400: #839ae5;
  --color-loch-ness-500: #6880d5;
  --color-loch-ness-600: #586db3;
  --color-loch-ness-700: #465790;
  --color-loch-ness-800: #31406c;
  --color-loch-ness-900: #212c4c;
  --color-loch-ness-950: #101932;
}

SCSS

$loch-ness: #5b71bc;
$loch-ness-rgb: 91, 113, 188;
$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);
}