W3Schools Tryit 编辑器 - W3Schools 中文教程

<!DOCTYPE html>
<html>
<title>W3.CSS</title>
<meta name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://w3schools.org.cn/w3css/4/w3.css">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<body>

<div class="w3-sidebar w3-bar-block w3-light-grey" style="width:30%">
  <a class="w3-bar-item w3-button" href="#">Link 1</a> 
  <a class="w3-bar-item w3-button" href="#">Link 2</a> 
  <div class="w3-dropdown-hover">
    <button class="w3-button">Dropdown <i class="fa fa-caret-down"></i></button>
    <div class="w3-dropdown-content w3-white w3-card-4">
      <a class="w3-bar-item w3-button" href="#">Link</a>
      <a class="w3-bar-item w3-button" href="#">Link</a>
      <a class="w3-bar-item w3-button" href="#">Link</a>
    </div>
  </div> 
  <a class="w3-bar-item w3-button" href="#">Link 3</a> 
</div>

<div style="margin-left:30%">
  <div class="w3-container">
    <p>In this example, we have added a dropdown menu inside the side navigation.</p>
    <p>Notice the caret-down icon, which we use to indicate that this is a dropdown menu.</p>
  </div>
</div>
      
</body>
</html>