CSS uses box-alignt and box-pack in the middle sub-element div

By using the box-align and box-pack attribute, the middle sub-frame div element:

div
{
width:350px;
height:100px;
border:1px solid black;

/* Firefox */
display:-moz-box;
-moz-box-pack:center;
-moz-box-align:center;

/* Safari、Opera 以及 Chrome */
display:-webkit-box;
-webkit-box-pack:center;
-webkit-box-align:center;

/* W3C */
display:box;
box-pack:center;
box-align:center;
}