<!DOCTYPE html>
<html>
<head>
<title>W3.CSS(w3cschool.cn)</title>
<meta name="viewport" content="width=device-width, initial-scale=1" charset="UTF-8">
<link rel="stylesheet" href="https://7npmedia.w3cschool.cn/w3.css">
</head>
<body>
<div class="w3-sidebar w3-bar-block w3-light-grey w3-card" style="width:160px;">
<a href="#" class="w3-bar-item w3-button">链接 1</a>
<a href="#" class="w3-bar-item w3-button" onclick="myAccFunc()">折叠栏</a>
<div id="demoAcc" class="w3-hide">
<a href="#" class="w3-bar-item w3-button">链接</a>
<a href="#" class="w3-bar-item w3-button">链接</a>
</div>
<div class="w3-dropdown-click">
<a href="#" class="w3-bar-item w3-button" onclick="myDropFunc()">下拉</a>
<div id="demoDrop" class="w3-dropdown-content">
<a href="#" class="w3-bar-item w3-button">链接</a>
<a href="#" class="w3-bar-item w3-button">链接</a>
</div>
</div>
<a href="#" class="w3-bar-item w3-button">链接 2</a>
<a href="#" class="w3-bar-item w3-button">链接 3</a>
</div>
<div class="w3-container" style="margin-left:160px">
<h2>侧栏折叠栏</h2>
<p>在此示例中,我们在侧面导航中添加了一个折叠栏和一个下拉菜单。</p>
<p>单击两者以了解它们之间的区别。折叠栏将按下内容,而下拉列表覆盖内容。</p>
</div>
<script>
function myAccFunc() {
var x = document.getElementById("demoAcc");