build.js

var Metalsmith = require('metalsmith');
var layouts = require('metalsmith-layouts');
var markdown = require('metalsmith-markdownit');
var sass = require('metalsmith-sass');
var footnote = require('markdown-it-footnote');

var md = markdown({
  html: true,
  typographer: true
});
md.parser.use(footnote);

Metalsmith(__dirname)
  .use(md)
  .use(layouts({ engine: 'handlebars', default: 'default.html' }))
  .use(sass({ outputDir: 'css' }))
  .build(function(err) {
    if (err) {
      throw err;
    }
  });