- The jumbotron text was not correctly centered between 750px and 970px
  width. Fixed by removing unnecessary HTML.
- Feature items flipped from 4 per row to 1 per row, without any 2-per row
  variant for medium-sized screens. Added a 2-per-row variant.
- The feature items had a fixed height which looked too tall on the
  large end of XS widths (one long item per row). Removed the fixed
  height and let the height adjust itself automatically.