1. <!DOCTYPE html>
    2. <html lang="zh-CN">
    3.   <head>
    4.     <meta charset="UTF-8" />
    5.     <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    6.     <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    7.     <link rel="stylesheet" href="index.css" />
    8.     <title>Index</title>
    9.   </head>
    11.   <body>
    12.     <div class="dropdown">
    13.       <button>名称</button>
    14.       <ul>
    15.         <li>沐</li>
    16.         <li>颖</li>
    17.         <li>汐</li>
    18.       </ul>
    19.     </div>
    20.   </body>
    21. </html>
    button {
  padding: 0;
  margin: 0;
  width: 100px;
  font-size: 16px;
  border: none;
  background-color: yellowgreen;
}
ul {
  padding: 0;
  margin: 0;
}
ul li {
  list-style: none;
}

.dropdown {
  width: 100px;
  margin: 0 auto;
  text-align: center;
  cursor: pointer;
}
.dropdown ul {
  display: none;
}
.dropdown:hover ul {
  display: block;
}