#3F6EA6

CSS

:root {
  --song-of-the-sea: #3f6ea6;
  --song-of-the-sea-rgb: 63 110 166;
  --song-of-the-sea-oklch: oklch(0.531 0.103 253.9);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(213 45% 45%);
  border-color: oklch(0.531 0.103 253.9);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #3f6ea6;
  --color-song-of-the-sea-50: #e2f7ff;
  --color-song-of-the-sea-100: #d2eaff;
  --color-song-of-the-sea-200: #b8d7ff;
  --color-song-of-the-sea-300: #95baec;
  --color-song-of-the-sea-400: #73a2da;
  --color-song-of-the-sea-500: #5389c9;
  --color-song-of-the-sea-600: #4774a9;
  --color-song-of-the-sea-700: #395d88;
  --color-song-of-the-sea-800: #264465;
  --color-song-of-the-sea-900: #1a2f47;
  --color-song-of-the-sea-950: #0a1b2e;
}

SCSS

$song-of-the-sea: #3f6ea6;
$song-of-the-sea-rgb: 63, 110, 166;
$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);
}