zola-theme-terminimal/sass/color/background_auto.scss

:root {

  @media (prefers-color-scheme: light) {
    --background: white;
  
    --color: #101010;
  }

  @media (prefers-color-scheme: dark) {
    --background: #101010;
  
    --color: #A9B7C6;
  }
}