1. compare old and new _config
  2. add mathjax + favicon to _include/head.html
  3. add notebook.html to _layouts
  4. keep aux_assets, pages, CNAME, robots.txt, this doc
  5. change _layouts/page.html to this: <div class="col-xl-10 offset-xl-1 col-lg-10 offset-lg-1">
  6. change font in assets/css/main.css (~line 16): 
     body {
 font-family: 'Open Sans', 'Helvetica Neue', Helvetica, Arial, sans-serif;
 ...