div-center.css

/*
* Horizontally center a div within a div using CSS
*/

#inner-new {
    margin: 0 auto; 
}

/*
* If you are targeting IE8+, it might be better to have this instead:
*/

#inner-ie {
    display: table;
    margin: 0 auto;
}

/*
* If you don't want to set a fixed width on the inner div you could do something like this
*/

#outer {
  width: 100%;
  text-align: center;
}

#inner {
  display: inline-block;
}

/* the last solution works best with padding */

Various CSS tricks to align div horizontally inside another div tag.