#00658A

CSS

:root {
  --blue-velvet: #00658a;
  --blue-velvet-rgb: 0 101 138;
  --blue-velvet-oklch: oklch(0.476 0.098 232.4);
}

.element {
  color: var(--blue-velvet);
  background-color: hsl(196 100% 27%);
  border-color: oklch(0.476 0.098 232.4);
}

Tailwind CSS v4

@theme {
  --color-blue-velvet: #00658a;
  --color-blue-velvet-50: #dbfbff;
  --color-blue-velvet-100: #c9eeff;
  --color-blue-velvet-200: #acdcf8;
  --color-blue-velvet-300: #85c0e2;
  --color-blue-velvet-400: #5ea9cf;
  --color-blue-velvet-500: #3391bc;
  --color-blue-velvet-600: #2d7a9f;
  --color-blue-velvet-700: #24627f;
  --color-blue-velvet-800: #16485e;
  --color-blue-velvet-900: #0f3242;
  --color-blue-velvet-950: #021e2a;
}

SCSS

$blue-velvet: #00658a;
$blue-velvet-rgb: 0, 101, 138;
$blue-velvet-light: mix(#fff, $blue-velvet, 20%);
$blue-velvet-dark: mix(#000, $blue-velvet, 20%);

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