How to put responsive background on col-md

<divclass="col-md-12">
        <div class="panel panel-default sharp">
            <div class="conteudo_me">

            </div>
        </div>
    </div><!-- /.col-md-12 -->

.conteudo_me {
background: url(../img/view.png);
height:255px;
width:100% auto;

background-position: 0px 280px; 
}