#004880

CSS

:root {
  --mermaid-blues: #004880;
  --mermaid-blues-rgb: 0 72 128;
  --mermaid-blues-oklch: oklch(0.396 0.113 250.2);
}

.element {
  color: var(--mermaid-blues);
  background-color: hsl(206 100% 25%);
  border-color: oklch(0.396 0.113 250.2);
}

Tailwind CSS v4

@theme {
  --color-mermaid-blues: #004880;
  --color-mermaid-blues-50: #dff8ff;
  --color-mermaid-blues-100: #ceebff;
  --color-mermaid-blues-200: #b2d8ff;
  --color-mermaid-blues-300: #8dbbf0;
  --color-mermaid-blues-400: #69a3df;
  --color-mermaid-blues-500: #468ace;
  --color-mermaid-blues-600: #3c75ae;
  --color-mermaid-blues-700: #305e8b;
  --color-mermaid-blues-800: #1f4567;
  --color-mermaid-blues-900: #143049;
  --color-mermaid-blues-950: #061c30;
}

SCSS

$mermaid-blues: #004880;
$mermaid-blues-rgb: 0, 72, 128;
$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);
}