<p dir="auto">col-md-12 don't have the css attribute float:left like others columns.<br>
The behavior is different (margin, padding, position ...)</p>
<p dir="auto">Example:<br>
`</p><div dir="auto"><p dir="auto"></p>
  <div dir="auto">.col-xs-6 .col-md-4</div>
  <div dir="auto">.col-xs-6 .col-md-4</div>
  <div dir="auto">.col-xs-6 .col-md-4</div>
</div>`
<p dir="auto">see: <a href="http://stackoverflow.com/questions/18428450/bootstrap-3-layout-with-panel-display-not-correct-on-small-device/18433782" rel="nofollow">http://stackoverflow.com/questions/18428450/bootstrap-3-layout-with-panel-display-not-correct-on-small-device/18433782</a></p>