#556AA6

CSS

:root {
  --loch-ness: #556aa6;
  --loch-ness-rgb: 85 106 166;
  --loch-ness-oklch: oklch(0.534 0.098 268.3);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(224 32% 49%);
  border-color: oklch(0.534 0.098 268.3);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #556aa6;
  --color-loch-ness-50: #eaf5ff;
  --color-loch-ness-100: #dbe7ff;
  --color-loch-ness-200: #c4d3ff;
  --color-loch-ness-300: #a4b5ea;
  --color-loch-ness-400: #869cd9;
  --color-loch-ness-500: #6b83c7;
  --color-loch-ness-600: #5b6fa8;
  --color-loch-ness-700: #485987;
  --color-loch-ness-800: #334164;
  --color-loch-ness-900: #222d47;
  --color-loch-ness-950: #121a2e;
}

SCSS

$loch-ness: #556aa6;
$loch-ness-rgb: 85, 106, 166;
$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);
}