css样式：

<style>
    .point{
    	position:relative;
    }
    .pop{
    	position:relative; 
    	width:90%;
    	height:100%; 
    	margin-top: 10%;
    	margin-left: 5%; 
    	margin-right: 5%;
    	background-color: white;
    	overflow:auto;
    }
    .shadow{
    	z-index:9;width:100%; 
    	height:100%;
    	left:0;
    	top:0; 
    	position:fixed;
    	background:rgba(0,0,0,0.3);
    }
</style>

div代码段：

<div style="">
<div class="point">
    <div class="pop">
   		弹窗内容
    </div>
</div>
</div>