#3A6FA6

CSS

:root {
  --naval: #3a6fa6;
  --naval-rgb: 58 111 166;
  --naval-oklch: oklch(0.531 0.104 251.1);
}

.element {
  color: var(--naval);
  background-color: hsl(211 48% 44%);
  border-color: oklch(0.531 0.104 251.1);
}

Tailwind CSS v4

@theme {
  --color-naval: #3a6fa6;
  --color-naval-50: #e1f8ff;
  --color-naval-100: #d0ebff;
  --color-naval-200: #b5d8ff;
  --color-naval-300: #92bbec;
  --color-naval-400: #6fa3da;
  --color-naval-500: #4e8ac9;
  --color-naval-600: #4375a9;
  --color-naval-700: #355d88;
  --color-naval-800: #234565;
  --color-naval-900: #183047;
  --color-naval-950: #081c2e;
}

SCSS

$naval: #3a6fa6;
$naval-rgb: 58, 111, 166;
$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);
}