Question

I have one content div with 960px of width and margin 0 auto (centralized), i want put one div occupying all the space of the left margin, how can i do that?

Answer 1

demo jsBin

  #container{
    position:relative;
    width:300px;/*change this*/
    margin:0 auto;
    height:200px;
    background:#cf5;
    padding-left:50%;
    margin-left:-150px; /*half the width*/
  }
  #centered{
    width:300px;
    height:100%;
    position:absolute;
    right:0px;
    background:#eea;
  }

HTML:

  <div id="container">  
    <div id="centered">centered</div>  
  </div>

HERE: http://jsbin.com/oluwos/3/edit is another way to do it.