#3A6FA5

CSS

:root {
  --naval: #3a6fa5;
  --naval-rgb: 58 111 165;
  --naval-oklch: oklch(0.53 0.103 250.7);
}

.element {
  color: var(--naval);
  background-color: hsl(210 48% 44%);
  border-color: oklch(0.53 0.103 250.7);
}

Tailwind CSS v4

@theme {
  --color-naval: #3a6fa5;
  --color-naval-50: #e1f8ff;
  --color-naval-100: #d0ebff;
  --color-naval-200: #b6d8ff;
  --color-naval-300: #92bbeb;
  --color-naval-400: #6fa3d9;
  --color-naval-500: #4e8ac8;
  --color-naval-600: #4375a8;
  --color-naval-700: #355e87;
  --color-naval-800: #244564;
  --color-naval-900: #183046;
  --color-naval-950: #081c2e;
}

SCSS

$naval: #3a6fa5;
$naval-rgb: 58, 111, 165;
$naval-light: mix(#fff, $naval, 20%);
$naval-dark: mix(#000, $naval, 20%);

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