As of now, there is a separate HTML::Tag::Macro module (that only contains the CSS class) and a HTML::Tag::Macro folder (containing Form, List and Table). This means for CSS, one needs to use HTML::Tag::Macro and for the others, the respective ::classname.
I think this is unnecessarily confusing. Either CSS has to go to the folder, or the others have to go to Macro.rakumod.