#3F6CB2

CSS

:root {
  --song-of-the-sea: #3f6cb2;
  --song-of-the-sea-rgb: 63 108 178;
  --song-of-the-sea-oklch: oklch(0.533 0.121 258.9);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(217 48% 47%);
  border-color: oklch(0.533 0.121 258.9);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #3f6cb2;
  --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: #729fe6;
  --color-song-of-the-sea-500: #5286d5;
  --color-song-of-the-sea-600: #4671b4;
  --color-song-of-the-sea-700: #385b91;
  --color-song-of-the-sea-800: #25436c;
  --color-song-of-the-sea-900: #192e4c;
  --color-song-of-the-sea-950: #0a1b32;
}

SCSS

$song-of-the-sea: #3f6cb2;
$song-of-the-sea-rgb: 63, 108, 178;
$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);
}