#3F6FA3

CSS

:root {
  --naval: #3f6fa3;
  --naval-rgb: 63 111 163;
  --naval-oklch: oklch(0.532 0.098 251.8);
}

.element {
  color: var(--naval);
  background-color: hsl(211 44% 44%);
  border-color: oklch(0.532 0.098 251.8);
}

Tailwind CSS v4

@theme {
  --color-naval: #3f6fa3;
  --color-naval-50: #e2f7ff;
  --color-naval-100: #d2eaff;
  --color-naval-200: #b8d7fe;
  --color-naval-300: #95bbe9;
  --color-naval-400: #73a2d7;
  --color-naval-500: #538ac5;
  --color-naval-600: #4774a6;
  --color-naval-700: #395d85;
  --color-naval-800: #264563;
  --color-naval-900: #1a2f45;
  --color-naval-950: #0a1c2d;
}

SCSS

$naval: #3f6fa3;
$naval-rgb: 63, 111, 163;
$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);
}