#004576

CSS

:root {
  --mermaid-blues: #004576;
  --mermaid-blues-rgb: 0 69 118;
  --mermaid-blues-oklch: oklch(0.381 0.103 248);
}

.element {
  color: var(--mermaid-blues);
  background-color: hsl(205 100% 23%);
  border-color: oklch(0.381 0.103 248);
}

Tailwind CSS v4

@theme {
  --color-mermaid-blues: #004576;
  --color-mermaid-blues-50: #e0f8ff;
  --color-mermaid-blues-100: #cfebff;
  --color-mermaid-blues-200: #b4d8ff;
  --color-mermaid-blues-300: #8fbceb;
  --color-mermaid-blues-400: #6ca4d8;
  --color-mermaid-blues-500: #498bc7;
  --color-mermaid-blues-600: #3f76a8;
  --color-mermaid-blues-700: #325e87;
  --color-mermaid-blues-800: #214564;
  --color-mermaid-blues-900: #163046;
  --color-mermaid-blues-950: #071c2e;
}

SCSS

$mermaid-blues: #004576;
$mermaid-blues-rgb: 0, 69, 118;
$mermaid-blues-light: mix(#fff, $mermaid-blues, 20%);
$mermaid-blues-dark: mix(#000, $mermaid-blues, 20%);

.element {
  color: $mermaid-blues;
  box-shadow: 0 0 0 2px rgba($mermaid-blues, 0.35);
}