code: function() {
  
        var book = this;
  
        if (!isEbook(book)) {
          return;
        }
  
        var outputDirectory = path.join(book.output.root(), '/gitbook/gitbook-plugin-prism');
        var outputFile = path.resolve(outputDirectory, 'prism-ebook.css');
        var inputFile = path.resolve(__dirname, './prism-ebook.css');
        mkdirp.sync(outputDirectory);
  
        try {
          fs.writeFileSync(outputFile, fs.readFileSync(inputFile));
        } catch (e) {
          console.warn('Failed to write prism-ebook.css. See https://git.io/v1LHY for side effects.');
          console.warn(e);
        }
  
      }
docs: Manually copy prism-ebook.css into the temporary directory that Gitbook uses for inlining styles from this plugin. The getAssets() (above) function can't be leveraged because ebook-prism.css lives outside the folder referenced by this plugin's config.  @Inspiration https://github.com/GitbookIO/plugin-styles-less/blob/master/index.js#L8