Hi,
I found the way for having full banner~
Following the steps mentioned in above posts, then change the /themes/default-bootstrap/css/modules/homeslider/homeslider.css as following
#homepage-slider {
padding-left: 0;
padding-right: 0;
margin-bottom: 14px;
width:100%; /*new*/
max-width: 100%;
max-height: 100%;
overflow: hidden;
position: relative;
z-index: 1;
/*float: left;*/ }