Timeline is a new component for showing posts in a left-right alternate order. It consists of 4 classes:
.timeline: The main wrapper class.
          .timeline-post: Each one of the posts in your timeline.
          .timeline-post-marker: Inside .timeline-post, this class is the 'dot' that connects to the main center line.
          .timeline-post-content: Inside .timeline-post, the container where you can put any content and style it however you want.
          Available variables:
$timeline-bg: The color of the lines.
          $timeline-post-margin-top: The spacing between posts.