#4B6D9F

CSS

:root {
  --song-of-the-sea: #4b6d9f;
  --song-of-the-sea-rgb: 75 109 159;
  --song-of-the-sea-oklch: oklch(0.531 0.088 257.9);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(216 36% 46%);
  border-color: oklch(0.531 0.088 257.9);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #4b6d9f;
  --color-song-of-the-sea-50: #e7f6ff;
  --color-song-of-the-sea-100: #d7e9ff;
  --color-song-of-the-sea-200: #bfd6fb;
  --color-song-of-the-sea-300: #9db9e5;
  --color-song-of-the-sea-400: #7ea0d3;
  --color-song-of-the-sea-500: #6187c0;
  --color-song-of-the-sea-600: #5273a2;
  --color-song-of-the-sea-700: #415c82;
  --color-song-of-the-sea-800: #2d4361;
  --color-song-of-the-sea-900: #1f2f44;
  --color-song-of-the-sea-950: #0e1b2c;
}

SCSS

$song-of-the-sea: #4b6d9f;
$song-of-the-sea-rgb: 75, 109, 159;
$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);
}