preline/src/plugins/collapse/variants.css

Preline UI is an open-source set of prebuilt UI components based on the utility-first Tailwind CSS framework.

@custom-variant hs-collapse-open {

  &.hs-collapse.open {
    @slot;
  }

  &.hs-collapse-toggle.open {
    @slot;
  }

  .hs-collapse.open & {
    @slot;
  }

  .hs-collapse-toggle.open & {
    @slot;
  }
}