svelte-windicss-preprocess: ParseError: Identifier `deep` is expected

[!] (plugin svelte) ParseError: Identifier `deep` is expected
node_modules/@responsive-ui/loader/src/Loader.svelte
34:   border-width: 2px;
35: }
36: // .responsive-ui-loader__spinner:after {
     ^
37:   //   content: "";
38:   //   width: 5px;

The comment in <style> is identified as deep selector.