code: function buildStyles() {
    return Promise.resolve()
      // Create the dist folder if it doesn't exist
      .then(() => {
        if(!FS.existsSync(Path.join(__dirname, 'dist'))) {
          return FS.mkdirAsync(Path.join(__dirname, 'dist'));
        }
      })
  
      // Generate minified stylesheet
      .then(() => {
        let file = Path.join(__dirname, 'source/css/shoelace.css');
        let css = FS.readFileSync(file, 'utf8');
  
        return PostCSS([
          AtImport,
          CSSnext({
            features: {
              rem: false
            }
          }),
          CSSnano({
            autoprefixer: false,
            safe: true
          })
        ]).process(css, { from: file });
      })
  
      // Write stylesheet to dist
      .then((result) => {
        let file = Path.join(__dirname, 'dist/shoelace.css');
  
        // Update {{version}} in CSS since it's not processed with Handlebars
        result.css = result.css.replace(/\{\{version\}\}/g, __version);
  
        // Output a message
        console.log(Chalk.green('CSS processed: %s! 🦋'), Path.relative(__dirname, file));
  
        // Write output file
        return FS.writeFileAsync(file, result.css, 'utf8');
      });
  }
docs: Builds all stylesheets.  Returns a promise.