Adjust styles for the columns' subheadings

* Put both subheadings definitions in base.less, because
  they are the same.
* Apply "word-wrap: break-word;" to cx-column__content,
  because it's relevant there, but not to the subheadings.
* Set explicit for the subheading height, because
  the language name and the "view page" link can be longer
  than one line.

Change-Id: Ie6fdc0657e5cfdfef9e91f234c2dc1b53b6be5be
Merge "Adjust styles for the columns' subheadings"