4. Add a responsive table, which will scroll horizontally on small viewports.

Add a table with a few rows and columns. Note how the table is poorly styled. Note that when you resize the window to be very narrow the table wraps across many lines trying to fit within the width. Add the .table class as shown at http://getbootstrap.com/css/#tables-example. The styling is much better. Now nest the table inside a <div class="table-responsive"> as shown at http://getbootstrap.com/css/#tables-responsive. Note that when you resize the window to be very narrow the table scrolls horizontally.