#00416D

CSS

:root {
  --mermaid-blues: #00416d;
  --mermaid-blues-rgb: 0 65 109;
  --mermaid-blues-oklch: oklch(0.365 0.095 246.7);
}

.element {
  color: var(--mermaid-blues);
  background-color: hsl(204 100% 21%);
  border-color: oklch(0.365 0.095 246.7);
}

Tailwind CSS v4

@theme {
  --color-mermaid-blues: #00416d;
  --color-mermaid-blues-50: #e1f8ff;
  --color-mermaid-blues-100: #d0ebff;
  --color-mermaid-blues-200: #b5d8fc;
  --color-mermaid-blues-300: #91bce6;
  --color-mermaid-blues-400: #6fa4d4;
  --color-mermaid-blues-500: #4d8cc2;
  --color-mermaid-blues-600: #4276a3;
  --color-mermaid-blues-700: #355f83;
  --color-mermaid-blues-800: #234661;
  --color-mermaid-blues-900: #173044;
  --color-mermaid-blues-950: #081c2c;
}

SCSS

$mermaid-blues: #00416d;
$mermaid-blues-rgb: 0, 65, 109;
$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);
}