#586AA4

CSS

:root {
  --loch-ness: #586aa4;
  --loch-ness-rgb: 88 106 164;
  --loch-ness-oklch: oklch(0.535 0.094 269.9);
}

.element {
  color: var(--loch-ness);
  background-color: hsl(226 30% 49%);
  border-color: oklch(0.535 0.094 269.9);
}

Tailwind CSS v4

@theme {
  --color-loch-ness: #586aa4;
  --color-loch-ness-50: #ebf4ff;
  --color-loch-ness-100: #dce7ff;
  --color-loch-ness-200: #c6d3fd;
  --color-loch-ness-300: #a6b5e8;
  --color-loch-ness-400: #899cd7;
  --color-loch-ness-500: #6e83c5;
  --color-loch-ness-600: #5d6fa6;
  --color-loch-ness-700: #4a5885;
  --color-loch-ness-800: #344163;
  --color-loch-ness-900: #242d46;
  --color-loch-ness-950: #131a2d;
}

SCSS

$loch-ness: #586aa4;
$loch-ness-rgb: 88, 106, 164;
$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);
}