特效描述：css3悬浮 返回顶部按钮 悬停显示 二维码特效，css3 右悬浮导航伸缩效果滚动切换
代码结构
1. 引入CSS
<link type="text/css" rel="stylesheet" href="css/style.css"> <link type="text/css" rel="stylesheet" href="css/style.css">
2. HTML代码
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>无标题文档</title>
</head>
<body style="height:2000px;">
顶部
<br />
<div class="toolbar">
<a href="###" class="toolbar-item toolbar-item-weixin">
<span class="toolbar-layer"></span>
</a>
<a href="###" class="toolbar-item toolbar-item-feedback"></a>
<a href="###" class="toolbar-item toolbar-item-app">
<span class="toolbar-layer"></span>
</a>
<a href="javascript:scroll(0,0)" id="top" class="toolbar-item toolbar-item-top"></a>
</div>
</body>
</html>
