joomla/joomla-cms — pull request #1793 by alam5131 (2013-08-22 04:36:51+00:00)
Title: Edit ".thumbnails > li" under "@media (max-width: 767px)"

We have to changer "float:none" to "float:left" because it show images in one after one in media manager when user use:

To insert image in article -> When a user access media manager.
To insert image in Custom HTML -> When a user access media manager.