#5AA3C8

CSS

:root {
  --sub-zero: #5aa3c8;
  --sub-zero-rgb: 90 163 200;
  --sub-zero-oklch: oklch(0.683 0.091 232.3);
}

.element {
  color: var(--sub-zero);
  background-color: hsl(200 50% 57%);
  border-color: oklch(0.683 0.091 232.3);
}

Tailwind CSS v4

@theme {
  --color-sub-zero: #5aa3c8;
  --color-sub-zero-50: #ddfaff;
  --color-sub-zero-100: #cbeeff;
  --color-sub-zero-200: #afdbf6;
  --color-sub-zero-300: #89c0df;
  --color-sub-zero-400: #64a8cb;
  --color-sub-zero-500: #3c90b8;
  --color-sub-zero-600: #357a9c;
  --color-sub-zero-700: #2a627d;
  --color-sub-zero-800: #1b485c;
  --color-sub-zero-900: #123240;
  --color-sub-zero-950: #041e29;
}

SCSS

$sub-zero: #5aa3c8;
$sub-zero-rgb: 90, 163, 200;
$sub-zero-light: mix(#fff, $sub-zero, 20%);
$sub-zero-dark: mix(#000, $sub-zero, 20%);

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