HTML 和 CSS 的多级悬停导航栏

Question

所以我正在查看 w3schools.com 上的代码，其中有一些很好的例子，我正试图从中找出正反面。但他们不提供有关自定义第三级菜单代码的说明。谁能帮我分解一下这段代码，这样我就可以随意添加多级菜单了？

<!doctype html>
<html>
<head>
<meta charset="utf-8" name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<title>Title</title>
<style>
body {
  font-family: Arial, Helvetica, sans-serif;
}

.navbar {
  overflow: hidden;
  background-color: #333;
}

.navbar a {
  float: left;
  font-size: 16px;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

.dropdown {
  float: left;
  overflow: hidden;
}

.dropdown .dropbtn {
  font-size: 16px;  
  border: none;
  outline: none;
  color: white;
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit;
  margin: 0;
}

.navbar a:hover, .dropdown:hover .dropbtn {
  background-color: red;
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
}

.dropdown-content a {
  float: none;
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}

.dropdown-content a:hover {
  background-color: #ddd;
}

.dropdown:hover .dropdown-content {
  display: block;
}
</style>
</head>
<body>

<div class="navbar">
  <a href="#home">Home</a>
  <a href="#news">News</a>
  <div class="dropdown">
    <button class="dropbtn">Dropdown 
      <i class="fa fa-caret-down"></i>
    </button>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <a href="#">Link 3</a>
    </div>
  </div> 
</div>

<h3>Dropdown Menu inside a Navigation Bar</h3>
<p>Hover over the "Dropdown" link to see the dropdown menu.</p>



</body>
</html>

也有人可以在这里向我解释这段代码在哪里以及如何告诉浏览器导航栏的总宽度。我在这里尝试了其他人的代码，导航栏只停留在 150 像素。当我更改宽度值时，它得到了所有错误。所以我知道我只是不明白这是在代码中确定的位置。

更新：感谢其中一个答案，我弄清楚了如何获得三级菜单，并通过让菜单向右弹出来摸索着。现在我的问题是它扩展了“Link 3”下的下拉菜单，就好像它为下面的链接腾出了空间。我将如何删除它？这是我当前的代码：

<!doctype html>
<html>
<head>
<meta charset="utf-8" name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<title>Title</title>
<style>
body {
  font-family: Arial, Helvetica, sans-serif;
}

.navbar {
  overflow: hidden;
  background-color: #333;
}

.navbar a {
  float: left;
  font-size: 16px;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

.dropdown {
  float: left;
  overflow: hidden;
}

.dropdown .dropbtn {
  font-size: 16px;  
  border: none;
  outline: none;
  color: white;
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit;
  margin: 0;
  width: 100%; /*red background color width*/
  text-align: start; /*text inside in red background color*/
}

.navbar a:hover, .dropdown:hover .dropbtn {
  background-color: red;
}

.dropdown-content-sub {
  display: none;
  position: relative;
  top: -46px;
  right: -300px;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px; /*block width*/
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px; /*block width*/
}

.dropdown-content a {
  float: none;
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}

.dropdown-content a:hover {
  background-color: #ddd;
}

.dropdown:hover .dropdown-content {
  display: block;
}

.dropdown-sub:hover .dropdown-content-sub {
  display: block;
}

</style>
</head>
<body>
        
<div class="navbar">
  <a href="#home">Home</a>
  <a href="#news">News</a>
  <div class="dropdown">
    <button class="dropbtn">Dropdown 
      <i class="fa fa-caret-down"></i>
    </button>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <div class="dropdown-sub">
    <button class="dropbtn">Link 3 
      <i class="fa fa-caret-right"></i>
    </button>
    <div class="dropdown-content-sub">
      <a href="#">Link 4</a>
      <a href="#">Link 5</a>
      <a href="#">Link 6</a>
    </div>
  </div> 
    </div>
  </div> 
</div>

<h3>Dropdown Menu inside a Navigation Bar</h3>
<p>Hover over the "Dropdown" link to see the dropdown menu.</p>



</body>
</html>

更新 2 最后：看来我将第三层的位置从绝对位置更改为相对位置导致了不良效果。只需将其切换回去即可解决，现在一切正常。 :) 之后我不得不更改按钮的“顶部”位置，但这很容易弄清楚。现在我应该能够将我的链接放在每个菜单项中，我很高兴去！ :) 感谢您的帮助！

Answer 1

查看 OP 中的更新。感谢@JannesCarpentier 和另一位匿名用户的帮助！这是从 w3schools.com 调整的代码以获得 3 层悬停导航栏。

<!doctype html>
<html>
<head>
<meta charset="utf-8" name="viewport" content="width=device-width, initial-scale=1">
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<title>Title</title>
<style>
body {
  font-family: Arial, Helvetica, sans-serif;
}

.navbar {
  overflow: hidden;
  background-color: #333;
}

.navbar a {
  float: left;
  font-size: 16px;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

.dropdown {
  float: left;
  overflow: hidden;
}

.dropdown .dropbtn {
  font-size: 16px;  
  border: none;
  outline: none;
  color: white;
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit;
  margin: 0;
  width: 100%; /*red background color width*/
  text-align: start; /*text inside in red background color*/
}

.navbar a:hover, .dropdown:hover .dropbtn {
  background-color: red;
}

.dropdown-content-sub {
  display: none;
  position: absolute;
  top: 85px;
  right: -300px;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px; /*block width*/
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px; /*block width*/
}

.dropdown-content a {
  float: none;
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}

.dropdown-content a:hover {
  background-color: #ddd;
}

.dropdown:hover .dropdown-content {
  display: block;
}

.dropdown-sub:hover .dropdown-content-sub {
  display: block;
}

</style>
</head>
<body>
        
<div class="navbar">
  <a href="#home">Home</a>
  <a href="#news">News</a>
  <div class="dropdown">
    <button class="dropbtn">Dropdown 
      <i class="fa fa-caret-down"></i>
    </button>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <div class="dropdown-sub">
    <button class="dropbtn">Link 3 
      <i class="fa fa-caret-right"></i>
    </button>
    <div class="dropdown-content-sub">
      <a href="#">Link 4</a>
      <a href="#">Link 5</a>
      <a href="#">Link 6</a>
    </div>
  </div> 
    </div>
  </div> 
</div>

<h3>Dropdown Menu inside a Navigation Bar</h3>
<p>Hover over the "Dropdown" link to see the dropdown menu.</p>



</body>
</html>

.navbar {
  overflow: hidden;
  background-color: #333;
}

.navbar a {
  float: left;
  font-size: 16px;
  color: white;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
}

.dropdown {
  float: left;
  overflow: hidden;
}

.dropdown .dropbtn {
  font-size: 16px;
  border: none;
  outline: none;
  color: white;
  padding: 14px 16px;
  background-color: inherit;
  font-family: inherit;
  margin: 0;
  width: 100%; /*red background color width*/
  text-align: start; /*text inside in red background color*/
}

.navbar a:hover, .dropdown:hover .dropbtn {
  background-color: red;
}

.dropdown-content-sub {
  display: none;
  position: absolute;
  top: 85px;
  right: -300px;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px; /*block width*/
}

.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f9f9f9;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
  z-index: 1;
  width: 300px; /*block width*/
}

.dropdown-content a {
  float: none;
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
  text-align: left;
}

.dropdown-content a:hover {
  background-color: #ddd;
}

.dropdown:hover .dropdown-content {
  display: block;
}

.dropdown-sub:hover .dropdown-content-sub {
  display: block;
}

<div class="navbar">
  <a href="#home">Home</a>
  <a href="#news">News</a>
  <div class="dropdown">
    <button class="dropbtn">Dropdown
      <i class="fa fa-caret-down"></i>
    </button>
    <div class="dropdown-content">
      <a href="#">Link 1</a>
      <a href="#">Link 2</a>
      <div class="dropdown-sub">
    <button class="dropbtn">Link 3
      <i class="fa fa-caret-right"></i>
    </button>
    <div class="dropdown-content-sub">
      <a href="#">Link 4</a>
      <a href="#">Link 5</a>
      <a href="#">Link 6</a>
    </div>
  </div>
    </div>
  </div>
</div>

HTML 和 CSS 的多级悬停导航栏

Multi-level Hover Navigation Bar with HTML and CSS

html

css

navigation

hover

dropdown