SOURCE

console 命令行工具 X clear

                    
>
console
<div class="parent">
    <div class="child">1212</div>
</div>
.parent {
    display: table-cell;
    width: 200px;
    height: 200px;
    border: 1px solid;
    vertical-align: middle;
}

.child {
    width: 100px;
    height: 100px;
    margin: 0 auto;
    background-color: #699;
}