Most of this is stock HTML and CSS from the Readme.io website.

For the most part, the only changes you will need to make are in Phoenix_files/custom.scss.

Make sure to install Sass and then run

sass --watch ./Phoenix_files/custom.scss

That will make sure to update the css as you are working on it.

Moving to Readme.io

Before copying custom.css to Readme.io, remember to remove the selector for .header h1.navbar-brand a. That is only used in development so the logo shows up.