website/static/src/scss/_mixins.scss

@mixin dark-mode {
  // Ensure animations aren't for the initial transition
  html.dark-mode-animate & {
    transition-duration: 0.5s;
    transition-property: color, background-color, border-color, filter,
      box-shadow;
  }

  html.dark-mode & {
    @content;
  }
}