html - Twitter Bootstrap Responsive Background-Image inside Div

Question

How i can modify #bg image so it would be responsive, resizable and proportional in all browser?

HTML:

 <div class="container">
       <div class="row">
          <div class="col-md-2"></div>

            <div class="col-md-8 col-sm-6 col-xs-12 well" id="bg">

               </div>

            <div class="col-md-2"></div>
       </div>
  </div>

css:

@import url('bootstrap.min.css');

body{
    background: url('../img/bg.jpg') no-repeat center center fixed;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
    background-size: cover;
    margin-top: 12%;    
}

#bg{
    background:url('../img/con_bg4.png') no-repeat center center;
    height: 500px;
}

Answer 1

I found a solution.

background-size:100% auto;