#5373A9

CSS

:root {
  --song-of-the-sea: #5373a9;
  --song-of-the-sea-rgb: 83 115 169;
  --song-of-the-sea-oklch: oklch(0.555 0.092 260.5);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(218 34% 49%);
  border-color: oklch(0.555 0.092 260.5);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #5373a9;
  --color-song-of-the-sea-50: #e7f6ff;
  --color-song-of-the-sea-100: #d8e9ff;
  --color-song-of-the-sea-200: #bfd5fd;
  --color-song-of-the-sea-300: #9eb8e7;
  --color-song-of-the-sea-400: #7f9fd5;
  --color-song-of-the-sea-500: #6286c3;
  --color-song-of-the-sea-600: #5372a5;
  --color-song-of-the-sea-700: #425b84;
  --color-song-of-the-sea-800: #2e4362;
  --color-song-of-the-sea-900: #1f2e45;
  --color-song-of-the-sea-950: #0f1b2d;
}

SCSS

$song-of-the-sea: #5373a9;
$song-of-the-sea-rgb: 83, 115, 169;
$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);
}