Developer Docs - Developer Codex - Use of Bootstrap Grid/Row/Column

You usually don't need to include extra .row .col-md-12 divs as shown below:

  

    ...
  

(unless you need to use floats inside the column)

A bootstrap row has a margin of -15px, and a bootstrap column has a margin of 15px. The two divs effectively cancel each other, and are generally not needed inside of Rock blocks.

Example:

https://codepen.io/garrettjohnson/pen/jOPWMpa?editors=1000