我正试图在下拉菜单上添加转换延迟属性，但它不起作用。我不知道为什么，我也在stackoverflow上搜索了不同的问题，但没有一个对我有效。这是我的代码：
<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">
<div class="header">
<h2>Mega Menu</h2>
</div>
<div class="row">
<div class="column">
<h3>Category 1</h3>
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
<div class="column">
<h3>Category 2</h3>
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
<div class="column">
<h3>Category 3</h3>
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
</div>
</div>
</div>
</div>
我的css代码在这里：
/* Show the dropdown menu on hover */
.dropdown:hover .dropdown-content {
display: block;
}
我的代码的JSbin
我还使用了visibility属性，而不是display，但它对我不起作用。您的回答将大大增加我的知识。提前谢谢。
您的代码中没有任何动画/转换。正如您所知，您无法设置显示属性的动画。使用动画:
/* Navbar container */
.navbar {
overflow: hidden;
background-color: #333;
font-family: Arial;
}
/* Links inside the navbar */
.navbar a {
float: left;
font-size: 16px;
color: white;
text-align: center;
padding: 14px 16px;
text-decoration: none;
}
/* The dropdown container */
.dropdown {
float: left;
overflow: hidden;
}
/* Dropdown button */
.dropdown .dropbtn {
font-size: 16px;
border: none;
outline: none;
color: white;
padding: 14px 16px;
background-color: inherit;
font: inherit; /* Important for vertical align on mobile phones */
margin: 0; /* Important for vertical align on mobile phones */
}
/* Add a red background color to navbar links on hover */
.navbar a:hover, .dropdown:hover .dropbtn {
background-color: red;
}
/* Dropdown content (hidden by default) */
.dropdown-content {
display: none;
position: absolute;
background-color: #f9f9f9;
width: 100%;
left: 0;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
/* addition to your existing code */
opacity: 0;
visibility: hidden;
transition: opacity 500ms, visibility 500ms;
}
/* Mega Menu header, if needed */
.dropdown-content .header {
background: red;
padding: 16px;
color: white;
}
/* Show the dropdown menu on hover */
.dropdown:hover .dropdown-content {
display: block;
/* addition to your existing code */
visibility: visible;
opacity: 1;
animation: fade 1s;
}
/* addition to your existing code */
@keyframes fade {
0% {
opacity: 0;
}
100% {
opacity: 1;
}
}
/* Create three equal columns that floats next to each other */
.column {
float: left;
width: 33.33%;
padding: 10px;
background-color: #ccc;
height: 250px;
}
/* Style links inside the columns */
.column a {
float: none;
color: black;
padding: 16px;
text-decoration: none;
display: block;
text-align: left;
}
/* Add a background color on hover */
.column a:hover {
background-color: #ddd;
}
/* Clear floats after the columns */
.row:after {
content: "";
display: table;
clear: both;
}
@media screen and (max-width: 600px) {
.column {
width: 100%;
height: auto;
}
}<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width">
<title>JS Bin</title>
</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">
<div class="header">
<h2>Mega Menu</h2>
</div>
<div class="row">
<div class="column">
<h3>Category 1</h3>
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
<div class="column">
<h3>Category 2</h3>
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
<div class="column">
<h3>Category 3</h3>
<a href="#">Link 1</a>
<a href="#">Link 2</a>
<a href="#">Link 3</a>
</div>
</div>
</div>
</div>
</div>
</body>
</html>要了解有关动画/过渡的更多信息，您可以查看：转换动画