CSS: Bootstrap: Setting Up Bootstrap Using The Bootstrap CDN (Bootstrap 4)

"Bootstrap is the most popular HTML, CSS, and JS Framework for developing responsive, mobile first projects on the web."  - getbootstrap.com

Brief Introduction:

Bootstrap is a front-end framework using HTML, CSS and JavaScript to build menus, navigations, layouts, forms, tables, and etc.  What is special about Bootstrap is that mobile-first, and responsive design is it's default behavior.  Okay, hold on, let me put my professor's glasses on!

Okay class here goes:

Mobile-First Design:  You design your site for mobile devices first so the desktop version is second class citizen.