css在盒子中垂直居中和固定居中

顶部固定居中

 <div class="w960 fixed">
        我是固定的
    </div>

.w960{
 960px;
margin:0 auto;
}
.fixed{
position: absolute;
top:0;
left: 0;
right: 0;
height: 90px;
background: #ececec;
}

垂直居中

<div id="box">
        <div class="son">ssss</div>
    </div>

#box {
     600px;
    height: 500px;
    position: relative;
    border: 1px solid #f00;
}
.son {
     100px;
    height: 100px;
    border: 1px solid #ecc;
    position: absolute;
    left: 50%;
    margin-left: -50px;
    top: 50%;
    margin-top: -50px;
}