#406DAA

CSS

:root {
  --song-of-the-sea: #406daa;
  --song-of-the-sea-rgb: 64 109 170;
  --song-of-the-sea-oklch: oklch(0.531 0.109 256.5);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(215 45% 46%);
  border-color: oklch(0.531 0.109 256.5);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #406daa;
  --color-song-of-the-sea-50: #e3f7ff;
  --color-song-of-the-sea-100: #d2eaff;
  --color-song-of-the-sea-200: #b8d6ff;
  --color-song-of-the-sea-300: #95b9ef;
  --color-song-of-the-sea-400: #74a1de;
  --color-song-of-the-sea-500: #5487cd;
  --color-song-of-the-sea-600: #4873ad;
  --color-song-of-the-sea-700: #395c8b;
  --color-song-of-the-sea-800: #274467;
  --color-song-of-the-sea-900: #1a2f48;
  --color-song-of-the-sea-950: #0a1b2f;
}

SCSS

$song-of-the-sea: #406daa;
$song-of-the-sea-rgb: 64, 109, 170;
$song-of-the-sea-light: mix(#fff, $song-of-the-sea, 20%);
$song-of-the-sea-dark: mix(#000, $song-of-the-sea, 20%);

.element {
  color: $song-of-the-sea;
  box-shadow: 0 0 0 2px rgba($song-of-the-sea, 0.35);
}