这个和前几个都是居中

by gothic

HTML

<div class="box">
  <div class="box2">Hello World</div>
</div>

CSS

.box { 
    width:200px; 
    background-color:yellow;
}
.box2{
     margin:0px auto; 
    background-color:gray; 
    color:white; 
    display:table; 
}