anchor.diff:  %% Public API
   %% ===================================================================
   
  +
   compile(Config, _AppFile) ->
       Options = options(Config),
  +    DocRoot = option(doc_root, Options),
  +    Stylesheets = option(stylesheets, Options),
  +    Targets = [normalize_path(Stylesheet, DocRoot)
  +                || Stylesheet <- Stylesheets],
  +    process(Targets, Options).
  +
  +process([], _Options) ->
  +    ok;
  +process(Targets, Options) ->
       OutDir = option(out_dir, Options),
       DocRoot = option(doc_root, Options),
       Stylus = option(stylus_path, Options),
       case stylus_is_present(Stylus) of
           true ->
  -            Cmd = lists:flatten([Stylus, " -o ", OutDir, " ", DocRoot]),
  +            Cmd = lists:flatten([Stylus, " -o ", OutDir, " ",
  +                                 string:join(Targets, " ")]),
               ShOpts = [{use_stdout, false}, return_on_error],
               case rebar_utils:sh(Cmd, ShOpts) of
                   {ok, _} ->
  
positive.code: 
  default(doc_root)     -> "priv/assets/stylesheets";
  default(out_dir)      -> "priv/www/stylesheets";
  default(stylus_path)  -> "/usr/local/bin/stylus".
  
  delete_each([]) ->
      ok;
  
negative.code:     end,
      delete_each(Rest).
  
  normalize_path(Path, Basedir) -> filename:join([Basedir, Path]).
  
  stylus_is_present(Stylus) -> filelib:is_file(Stylus).
  