#357BA7

CSS

:root {
  --zenith: #357ba7;
  --zenith-rgb: 53 123 167;
  --zenith-oklch: oklch(0.558 0.098 239.5);
}

.element {
  color: var(--zenith);
  background-color: hsl(203 52% 43%);
  border-color: oklch(0.558 0.098 239.5);
}

Tailwind CSS v4

@theme {
  --color-zenith: #357ba7;
  --color-zenith-50: #ddf9ff;
  --color-zenith-100: #ccedff;
  --color-zenith-200: #b0dafb;
  --color-zenith-300: #8abee5;
  --color-zenith-400: #65a6d2;
  --color-zenith-500: #408ec0;
  --color-zenith-600: #3778a2;
  --color-zenith-700: #2c6082;
  --color-zenith-800: #1c4760;
  --color-zenith-900: #133143;
  --color-zenith-950: #041d2b;
}

SCSS

$zenith: #357ba7;
$zenith-rgb: 53, 123, 167;
$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);
}