CSS - 3 column DIV with centering

http://stackoverflow.com/questions/8828249/center-div-within-a-div/8828698#8828698

HTML

<div class="headerContainer">
 <div class="centerDiv">center</div>
</div>

CSS

.headerContainer{
  width: 100%;
}

.centerDiv{
  width:80%;
  margin: 0 auto;
  background: gray;
}