There are currently only a limited set of styles available from the zotero.org web library. The web library has only a fraction of the functionality of the installed Zotero app, and it isn't intended to replace the app. What exactly is your use case here?
I believe that expanded style support online is planned in an upcoming major overhaul of the web library.
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I believe that expanded style support online is planned in an upcoming major overhaul of the web library.