#405C7E

CSS

:root {
  --mississippi-river: #405c7e;
  --mississippi-river-rgb: 64 92 126;
  --mississippi-river-oklch: oklch(0.468 0.065 253.8);
}

.element {
  color: var(--mississippi-river);
  background-color: hsl(213 33% 37%);
  border-color: oklch(0.468 0.065 253.8);
}

Tailwind CSS v4

@theme {
  --color-mississippi-river: #405c7e;
  --color-mississippi-river-50: #e9f6ff;
  --color-mississippi-river-100: #dae9fe;
  --color-mississippi-river-200: #c3d6f0;
  --color-mississippi-river-300: #a2b9d9;
  --color-mississippi-river-400: #84a1c5;
  --color-mississippi-river-500: #6889b1;
  --color-mississippi-river-600: #587495;
  --color-mississippi-river-700: #465d78;
  --color-mississippi-river-800: #324458;
  --color-mississippi-river-900: #222f3e;
  --color-mississippi-river-950: #111b27;
}

SCSS

$mississippi-river: #405c7e;
$mississippi-river-rgb: 64, 92, 126;
$mississippi-river-light: mix(#fff, $mississippi-river, 20%);
$mississippi-river-dark: mix(#000, $mississippi-river, 20%);

.element {
  color: $mississippi-river;
  box-shadow: 0 0 0 2px rgba($mississippi-river, 0.35);
}