#426FB5

CSS

:root {
  --song-of-the-sea: #426fb5;
  --song-of-the-sea-rgb: 66 111 181;
  --song-of-the-sea-oklch: oklch(0.543 0.121 258.9);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(217 47% 48%);
  border-color: oklch(0.543 0.121 258.9);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #426fb5;
  --color-song-of-the-sea-50: #e2f6ff;
  --color-song-of-the-sea-100: #d1e9ff;
  --color-song-of-the-sea-200: #b7d5ff;
  --color-song-of-the-sea-300: #94b8f6;
  --color-song-of-the-sea-400: #729fe5;
  --color-song-of-the-sea-500: #5386d5;
  --color-song-of-the-sea-600: #4771b4;
  --color-song-of-the-sea-700: #385b90;
  --color-song-of-the-sea-800: #25436b;
  --color-song-of-the-sea-900: #192e4c;
  --color-song-of-the-sea-950: #0a1b32;
}

SCSS

$song-of-the-sea: #426fb5;
$song-of-the-sea-rgb: 66, 111, 181;
$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);
}