Manipulating CSS Class Properties Using JavaScript

If you would like to look at this code, it can be viewed here:
HTML: https://github.com/Owen-Nathan/CS261/blob/master/topic7/index.html
JS: https://github.com/Owen-Nathan/CS261/blob/master/topic7/scripts.js

This is a basic header. We're going to dynamically Change its style!

This is just a paragraph. We're going to change it as well!