#2E5662

CSS

:root {
  --night-shift: #2e5662;
  --night-shift-rgb: 46 86 98;
  --night-shift-oklch: oklch(0.429 0.049 219.4);
}

.element {
  color: var(--night-shift);
  background-color: hsl(194 36% 28%);
  border-color: oklch(0.429 0.049 219.4);
}

Tailwind CSS v4

@theme {
  --color-night-shift: #2e5662;
  --color-night-shift-50: #e7f9ff;
  --color-night-shift-100: #d7ecf4;
  --color-night-shift-200: #bedae3;
  --color-night-shift-300: #9dbec9;
  --color-night-shift-400: #7ea6b2;
  --color-night-shift-500: #608e9d;
  --color-night-shift-600: #527884;
  --color-night-shift-700: #41606a;
  --color-night-shift-800: #2f474e;
  --color-night-shift-900: #1f3136;
  --color-night-shift-950: #0f1d21;
}

SCSS

$night-shift: #2e5662;
$night-shift-rgb: 46, 86, 98;
$night-shift-light: mix(#fff, $night-shift, 20%);
$night-shift-dark: mix(#000, $night-shift, 20%);

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