title: center fixed div within bootstrap container class for responsive layout
body: <p>I'd try to use margin percentage to apply the hack but since it's responsive I have no idea how to centering a fixed div in bootstrap container class. I run my experiment here:</p>
  
  <p><a href="http://jsbin.com/oqOsEGa/1" rel="nofollow">http://jsbin.com/oqOsEGa/1</a></p>
  
  <p>try to uncheck the position:fixed in developer tool, things go within the container, but I want to apply fixed but align in the container class of bootstrap, how?</p>