html - 我的导航栏下拉菜单无法正常工作

Question

My dropdown of the navigation bar is not working properly

I have tried to lookout on many forums. But none of them solved my problem.

我的导航栏不能正常工作，我用 CSS 和 HTML 做了它。

1) 合作伙伴和服务按钮的下拉箭头未显示。

2) 悬停或点击后应该出现一个下拉菜单，但它没有出现在我的屏幕上。

这些是我面临的问题。那么你们能帮我解决我的问题吗？

nav {
  margin: 0 auto;
  padding: 0;
  width: 78%;
  background-color: #757575;
}

.navbar navbar-default {
  background-color: #757575;
}

a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 50%;
}

.footer {
  position: fixed;
  left: 0;
  bottom: 0;
  width: 100%;
  background-color: #757575;
  color: white;
  text-align: left;
}


/* The navigation menu */

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


/* Navigation links */

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


/* The subnavigation menu */

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


/* Subnav button */

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


/* Add a red background color to navigation links on hover */

.navbar a:hover,
.subnav:hover .subnavbtn {
  background-color: red;
}


/* Style the subnav content - positioned absolute */

.subnav-content {
  display: none;
  position: absolute;
  left: 0;
  background-color: red;
  width: 100%;
  z-index: 1;
}


/* Style the subnav links */

.subnav-content a {
  float: left;
  color: white;
  text-decoration: none;
}


/* Add a grey background color on hover */

.subnav-content a:hover {
  background-color: #eee;
  color: black;
}


/* When you move the mouse over the subnav container, open the subnav content */

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

input[type=text] {
  width: 130px;
  -webkit-transition: width 0.4s ease-in-out;
  transition: width 0.4s ease-in-out;
}


/* When the input field gets focus, change its width to 100% */

input[type=text]:focus {
  width: 100%;
}

* {
  font-family: arial;
}

<div class="navbar">
  <a href="#home">Home</a>
  <div class="subnav">
    <button class="subnavbtn">About <i class="fa fa-caret-down"></i></button>
    <div class="subnav-content">
      <a href="#company">Company</a>
      <a href="#team">Team</a>
      <a href="#careers">Careers</a>
    </div>
  </div>
  <div class="subnav">
    <button class="subnavbtn">Services <i class="fa fa-caret-down"></i></button>
    <div class="subnav-content">
      <a href="#bring">Bring</a>
      <a href="#deliver">Deliver</a>
      <a href="#package">Package</a>
      <a href="#express">Express</a>
    </div>
  </div>
  <div class="subnav">
    <button class="subnavbtn">Partners <i class="fa fa-caret-down"></i></button>
    <div class="subnav-content">
      <a href="#link1">Link 1</a>
      <a href="#link2">Link 2</a>
      <a href="#link3">Link 3</a>
      <a href="#link4">Link 4</a>
    </div>
  </div>
  <a href="#contact">Contact</a>

</div>

Answer 1

添加字体 CSS文件

<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.9.0/css/all.css" rel="stylesheet"/>

nav {
  margin: 0 auto;
  padding: 0;
  width: 78%;
  background-color: #757575;
}

.navbar navbar-default {
  background-color: #757575;
}

a {
  float: left;
  display: block;
  color: #f2f2f2;
  text-align: center;
  padding: 14px 16px;
  text-decoration: none;
  font-size: 17px;
}

.center {
  display: block;
  margin-left: auto;
  margin-right: auto;
  width: 50%;
}

.footer {
  position: fixed;
  left: 0;
  bottom: 0;
  width: 100%;
  background-color: #757575;
  color: white;
  text-align: left;
}


/* The navigation menu */

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


/* Navigation links */

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


/* The subnavigation menu */

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


/* Subnav button */

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


/* Add a red background color to navigation links on hover */

.navbar a:hover,
.subnav:hover .subnavbtn {
  background-color: red;
}


/* Style the subnav content - positioned absolute */

.subnav-content {
  display: none;
  position: absolute;
  left: 0;
  background-color: red;
  width: 100%;
  z-index: 1;
}


/* Style the subnav links */

.subnav-content a {
  float: left;
  color: white;
  text-decoration: none;
}


/* Add a grey background color on hover */

.subnav-content a:hover {
  background-color: #eee;
  color: black;
}


/* When you move the mouse over the subnav container, open the subnav content */

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

input[type=text] {
  width: 130px;
  -webkit-transition: width 0.4s ease-in-out;
  transition: width 0.4s ease-in-out;
}


/* When the input field gets focus, change its width to 100% */

input[type=text]:focus {
  width: 100%;
}

* {
  font-family: arial;
}

<link href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/5.9.0/css/all.css" rel="stylesheet"/>
<div class="navbar">
  <a href="#home">Home</a>
  <div class="subnav">
    <button class="subnavbtn">About <i class="fa fa-caret-down"></i></button>
    <div class="subnav-content">
      <a href="#company">Company</a>
      <a href="#team">Team</a>
      <a href="#careers">Careers</a>
    </div>
  </div>
  <div class="subnav">
    <button class="subnavbtn">Services <i class="fa fa-caret-down"></i></button>
    <div class="subnav-content">
      <a href="#bring">Bring</a>
      <a href="#deliver">Deliver</a>
      <a href="#package">Package</a>
      <a href="#express">Express</a>
    </div>
  </div>
  <div class="subnav">
    <button class="subnavbtn">Partners <i class="fa fa-caret-down"></i></button>
    <div class="subnav-content">
      <a href="#link1">Link 1</a>
      <a href="#link2">Link 2</a>
      <a href="#link3">Link 3</a>
      <a href="#link4">Link 4</a>
    </div>
  </div>
  <a href="#contact">Contact</a>

</div>