鼠标悬停时下拉菜单未打开

如何解决鼠标悬停时下拉菜单未打开

我只是 HTML5 和 CSS 的开始。我正在尝试制作下拉菜单，但出了点问题。看了一会儿，但找不到我的错误。我希望有人愿意帮助我！下面是我的 CSS 编码。如果有一些问题或细节需要评论，我当然很想听听他们的意见。

*{
    margin: 0;
    padding: 0;
    front-family: century gothic;
}

header{
    background-image:linear-gradient(rgba(0,0.5),rgba(0,0.5)),url(image.jpg);
    height: 100vh;
    background-size: cover;
    background-position: center;
}

ul{
    float: right;
    list-style-type: none;
    margin-top: 25px;
}

ul li{
    display: inline-block;
}

ul li a{
    text-decoration:none;
    color:#fff;
    padding:5px 20px;
    border:2px solid transparent;
    transition: 0.8s ease;
}

ul li a:hover{
    background-color:#fff;
    color: #000;
}

ul li.active a{
    background-color:#fff;
    color: #000;
}

/* Dropdown Button */
.dropbtn {
  background-color: #fff;
  color: black;
  padding: 16px;
  font-size: 16px;
  border: black;
}

/* The container <div> - needed to position the dropdown content */
.dropdown {
  padding:10px 50px;
  display: inline-block;
}

/* Dropdown Content (Hidden by Default) */
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0.2);
  z-index: 1;
}

/* Links inside the dropdown */
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

.logo img{
    float:left;
    width: 150px;
    height: auto;
}

.main{
    max-width: 1200px;
    margin: auto;
}

.title{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%)
    
}

.title h1{
    color: #fff;
    font-size: 70px;
}

.button{
position: absolute;
    top: 62%;
    left: 50%;
    transform: translate(-50%,-50%);
    
}

.btn{
    border: 1px solid #fff;
    padding: 10px 30px;
    color: #fff;
    text-decoration: none;
    transition: 0.6s ease;
}

.btn:hover{
    background-color: #fff;
    color: #000;

}

解决方法

当您悬停时，您的 CSS 中没有任何内容告诉 .dropdown-content 出现。你可以尝试这样的事情。我已经复制了您的 CSS 并添加到其中，还添加了一些 HTML：

*{
    margin: 0;
    padding: 0;
    font-family: century gothic;
}

header{
    background-image:linear-gradient(rgba(0,0.5),rgba(0,0.5)),url(image.jpg);
    height: 100vh;
    background-size: cover;
    background-position: center;
}

ul {
    float: right;
    list-style-type: none;
    margin-top: 25px;
}

ul li{
    display: inline-block;
}

ul li a{
    text-decoration:none;
    color:#fff;
    padding:5px 20px;
    border:2px solid transparent;
    transition: 0.8s ease;
}

ul li a:hover{
    background-color:#fff;
    color: #000;
}

ul li.active a{
    background-color:#fff;
    color: #000;
}

/* Dropdown Button */
.dropbtn {
  background-color: #fff;
  color: black;
  padding: 16px;
  font-size: 16px;
  border: black;
}

/* The container <div> - needed to position the dropdown content */
.dropdown {
  padding:10px 50px;
  display: inline-block;
}

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

/* Dropdown Content (Hidden by Default) */
.dropdown-content {
  display: none;
  position: absolute;
  background-color: #f1f1f1;
  min-width: 160px;
  box-shadow: 0px 8px 16px 0px rgba(0,0.2);
  z-index: 1;
}

/* Links inside the dropdown */
.dropdown-content a {
  color: black;
  padding: 12px 16px;
  text-decoration: none;
  display: block;
}

.logo img{
    float:left;
    width: 150px;
    height: auto;
}

.main{
    max-width: 1200px;
    margin: auto;
}

.title{
    position: absolute;
    top: 50%;
    left: 50%;
    transform: translate(-50%,-50%)
    
}

.title h1{
    color: #fff;
    font-size: 70px;
}

.button{
position: absolute;
    top: 62%;
    left: 50%;
    transform: translate(-50%,-50%);
    
}

.btn{
    border: 1px solid #fff;
    padding: 10px 30px;
    color: #fff;
    text-decoration: none;
    transition: 0.6s ease;
}

.btn:hover{
    background-color: #fff;
    color: #000;
}

<header>
  <div class="dropbtn">show dropdown</div>
 
  <div class="dropdown">
    <div class="dropdown-content">
      <ul>
        <li><a href="">One</a></li>
        <li><a href="">Two</a></li>
        <li><a href="">Three</a></li>
       </ul>
    </div>
  </div>

</header>

我正在使用一般的兄弟选择器 ~，使我的 :hover CSS 工作。看到您的实际 HTML 后，我可以改进此答案。