#556AA7

CSS

:root {
  --loch-ness: #556aa7;
  --loch-ness-rgb: 85 106 167;
  --loch-ness-oklch: oklch(0.535 0.099 268.5);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(225 33% 49%);
  border-color: oklch(0.535 0.099 268.5);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #556aa7;
  --color-loch-ness-50: #eaf4ff;
  --color-loch-ness-100: #dbe7ff;
  --color-loch-ness-200: #c4d3ff;
  --color-loch-ness-300: #a4b5eb;
  --color-loch-ness-400: #869cda;
  --color-loch-ness-500: #6b83c8;
  --color-loch-ness-600: #5a6fa9;
  --color-loch-ness-700: #485988;
  --color-loch-ness-800: #324165;
  --color-loch-ness-900: #222d47;
  --color-loch-ness-950: #111a2e;
}

SCSS

$loch-ness: #556aa7;
$loch-ness-rgb: 85, 106, 167;
$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);
}