.banner > img
{
/*background: url('myimage);*/
background-repeat:no-repeat;
background-position: top center;
background-size: cover;
/*background-size: 100%;*/
-webkit-background-size: cover;
-moz-background-size: cover;
-o-background-size: cover;
}
please refer to the link for details:
Bootstrap 3 and Responsive Background Images
http://qnundrum.com/answer.php?q=865822
Twitter Bootstrap Layout tutorial
http://www.w3resource.com/twitter-bootstrap/layout-tutorial.php
An overview of Bootstrap, how to download and use, basic templates and examples, and more.