如何让DIV置顶，

shanwei0409

<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<meta name="viewport" content="maximum-scale=1.0,minimum-scale=1.0,user-scalable=0,width=device-width,initial-scale=1.0"/>
<title></title>
<link rel="stylesheet" type="text/css" href="../../css/style.css" />
<link rel="stylesheet" type="text/css" href="../../css/aui.css" />
<style>
body {
background-color: white;
}
div.flex-wrap {
-webkit-box-orient: vertical;
-webkit-flex-flow: column;
flex-flow: column;
height: 100%;
}
.showjk {
width: 40px;
height: 20px;
position: absolute;
bottom: 100px;
left: 20px;
z-index: 999;
}
</style>
</head>
<body>
<header class="aui-bar aui-bar-nav">
<div class="aui-title">
高速路况
</div>
<a class="aui-pull-right aui-btn aui-btn-outlined"> <span class="aui-iconfont aui-icon-search"></span> </a>
</header>
<div class="showjk" >
<div style="position:absolute;z-index: 100"><img src="../../image/u328.png">
</div>
<img src="../../image/u330.png">监控
</div>
<div class="zoom">
归位
</div>
</body>
</html>
<script type="text/javascript" src="../../script/SHA1.js"></script>
<script type="text/javascript" src="../../script/api.js"></script>
<script type="text/javascript" src="../../script/api_aui.js" ></script>
<script type="text/javascript">
apiready = function() {
var h = $api.dom('header').h;
api.openFrame({
name : 'map',
url : 'http://192.168.1.104:8080/hngs/open/pcView/svg',
rect : {
x : 0,
y : 45,
w : api.winWidth,
h : api.winHeight - 100
}
});

};
function showRoad() {
var header_h = $api.offset($api.dom('header')).h;
var hi = api.winHeight - 70;
api.openWin({
name : 'search',
url : 'search.html'
});
}

</script>
上面是我写的一个页面，如何让让DIV<div class="showjk" >
<div style="position:absolute;z-index: 100"><img src="../../image/u328.png">
</div>
<img src="../../image/u330.png">监控
</div> 一直置顶那，就像我们在使用百度地图的时候一样

shanwei0409

自己先顶一下