One of the biggest complaints about Drupal was the lack of a simple upgrade path from one major version to another. Since beginning to work with Drupal 4.7, I have been migrating custom websites, standard Drupal sites, Wordpress to Drupal, html to Drupal—you name it. And it was always a very exciting journey. By the time of 6 to 7, migrating content with data export and feeds become more of a routine exercise, but still quite time consuming.
One of the most pleasant surprises with Drupal 8 was the upgrade process.
Making colums: http://cssreference.io/#column-count
More about box-model: http://cssreference.io/#box-sizing
And overall great resource with excellent search tool http://cssreference.io/
