学习如何使用html和css样式将两张图片叠加到另一张图片上，实现微信扫一扫二维码效果
<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8"/>
<link rel="stylesheet" href="menuStyle.css"/>
<title>二维码扫一扫</title>
</head>
<style>
.top {
position: absolute;
z-index: 1;
margin-top: 1%;
margin-left: -280px;
transition: background-color 300ms;
transition-property: background-color;
transition-duration: 300ms;
transition-timing-function: ease;
transition-delay: 0s;
}
</style>
<body>
<div>
<a href="#"><img src='image/wenku_login.jpg' width="300" height="300"></a>
<a href="#"><img id="qrcode_saoyisao" class="top" src='image/saoyisao.png' width="300" height="300"></a>
</div>
<script src="image/jquery.js" type='text/javascript'></script>
</body>
<script type="text/javascript">
function scanPic() {
$("#qrcode_saoyisao").attr('src', 'image/saoyisao.png');
}
(function () {
let scanTime = 3 * 1000;
setInterval("scanPic()", scanTime);
})();
</script>
</html>
