#456DAA

CSS

:root {
  --song-of-the-sea: #456daa;
  --song-of-the-sea-rgb: 69 109 170;
  --song-of-the-sea-oklch: oklch(0.534 0.107 258.6);
}

.element {
  color: var(--song-of-the-sea);
  background-color: hsl(216 42% 47%);
  border-color: oklch(0.534 0.107 258.6);
}

Tailwind CSS v4

@theme {
  --color-song-of-the-sea: #456daa;
  --color-song-of-the-sea-50: #e4f6ff;
  --color-song-of-the-sea-100: #d4e9ff;
  --color-song-of-the-sea-200: #bbd6ff;
  --color-song-of-the-sea-300: #98b8ee;
  --color-song-of-the-sea-400: #77a0dd;
  --color-song-of-the-sea-500: #5987cc;
  --color-song-of-the-sea-600: #4c72ac;
  --color-song-of-the-sea-700: #3c5b8a;
  --color-song-of-the-sea-800: #294367;
  --color-song-of-the-sea-900: #1c2e48;
  --color-song-of-the-sea-950: #0c1b2f;
}

SCSS

$song-of-the-sea: #456daa;
$song-of-the-sea-rgb: 69, 109, 170;
$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);
}