#5B71B9

CSS

:root {
  --loch-ness: #5b71b9;
  --loch-ness-rgb: 91 113 185;
  --loch-ness-oklch: oklch(0.564 0.115 269.6);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(226 40% 54%);
  border-color: oklch(0.564 0.115 269.6);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #5b71b9;
  --color-loch-ness-50: #e9f4ff;
  --color-loch-ness-100: #dae7ff;
  --color-loch-ness-200: #c2d2ff;
  --color-loch-ness-300: #a2b4f3;
  --color-loch-ness-400: #839be3;
  --color-loch-ness-500: #6881d2;
  --color-loch-ness-600: #586db1;
  --color-loch-ness-700: #46578e;
  --color-loch-ness-800: #31406a;
  --color-loch-ness-900: #212c4b;
  --color-loch-ness-950: #111931;
}

SCSS

$loch-ness: #5b71b9;
$loch-ness-rgb: 91, 113, 185;
$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);
}