背景图片

css：

.zhegnshu-big,.zhegnshu-big-img{display: none;}
.zhegnshu-big{
background-color: #000000;
100%;
height: 100%;
left:0;
top:0;/*FF IE7*/
filter:alpha(opacity=70);/*IE*/ /*点击后背景透明效果*/
opacity:0.5;/*FF*/
z-index:10001;
position:fixed !important;/*FF IE7*/
position:absolute;/*IE6*/
}
.zhegnshu-big-img img{
position: fixed;top: 100px;left: 50%;z-index:10002;margin-left: -565px;
}

html:

<div class="zhegnshu-big"></div>
<div class="zhegnshu-big-img">
<img src="./uploadfile/0806/img.jpg">
</div>

js:

$(".box-sz-zhengming img").click(function(){
$(".zhegnshu-big,.zhegnshu-big-img").show();
});