元素居中显示的方法

 

{
        position: absolute;
        left: 50%;
        top: 50%;
        margin-left: -100px;
        margin-top: -100px;
        width: 200px;
        height: 200px;
    }

{
        position: absolute;
        margin: auto;
        left: 0;
        top: 0;
        right: 0;
        bottom: 0;
        width: 200px;
        height: 200px;
    }