<html>
<head>
<meta charset="UTF-8">
<title></title>
<style type="text/css">
.menu:hover .menucontent{
display: block;
}
.menucontent{
width: 120px;
display: none;
text-align: center;
border: 1px solid #ddd;
}
.menu .btn{
display: block;
width: 50px;
height: 20px;
text-align: center;
font-size: 14px;
background: red;
color: #fff;
}
</style>
</head>
<body>
<div class="menu">
<span class="btn">菜单</span>
<div class="menucontent">
<p>hello</p>
<p>world</p>
<p>helloWorld</p>
</div>
</div>
</body>
</html>
原文：https://www.cnblogs.com/150536FBB/p/11599339.html