水平居中
1
margin: 0 auto;
2
position: fixed;
left: 50%;
3
margin:auto;
position: absolute;
left: 0;
right: 0;
4
width: 500px;
height: 500px;
border: 1px #ccc solid;
background:red;
position:absolute;
left:50%;
border-radius: 5px;
-webkit-transform:translate(-50%);
5
width: 50px;
height: 50px;
position: absolute;
left: 50%;
margin-left: -25px;
垂直居中
width: 500px;
height: 500px;
border: 1px #ccc solid;
background:red;
position:absolute;
top:50%;
-webkit-transform:translate(0,-50%);
父元素加 display: table;
子元素加 display: table-cell; vertical-align: middle;
width: 50px;
height: 50px;
position: absolute;
top: 50%;
margin-top: -25px;
4
width: 500px;
height: 500px;
border: 1px #ccc solid;
position: absolute;
margin: auto;
top: 0;
bottom: 0;
