#4379A1

CSS

:root {
  --zenith: #4379a1;
  --zenith-rgb: 67 121 161;
  --zenith-oklch: oklch(0.556 0.085 242.5);
}

.element {
  color: var(--zenith);
  background-color: hsl(206 41% 45%);
  border-color: oklch(0.556 0.085 242.5);
}

Tailwind CSS v4

@theme {
  --color-zenith: #4379a1;
  --color-zenith-50: #e2f9ff;
  --color-zenith-100: #d1ecff;
  --color-zenith-200: #b6d9f7;
  --color-zenith-300: #93bde0;
  --color-zenith-400: #71a5cd;
  --color-zenith-500: #508dba;
  --color-zenith-600: #44779d;
  --color-zenith-700: #365f7e;
  --color-zenith-800: #25465d;
  --color-zenith-900: #193141;
  --color-zenith-950: #091d2a;
}

SCSS

$zenith: #4379a1;
$zenith-rgb: 67, 121, 161;
$zenith-light: mix(#fff, $zenith, 20%);
$zenith-dark: mix(#000, $zenith, 20%);

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