大多数按钮旨在易于单击。按钮的想法是要有一种简单，优雅的方式来浏览任何网页。它是人文科学上最好的发明之一。但是我找到了破坏它的方法。由于某种原因，通过在下拉按钮菜单中添加超棒的字体图标，它使整个按钮停止工作，除了它的外角。谁能帮我使整个按钮正常工作？这是怎么回事？
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<meta name="viewport" content="width=device-width, initial-scale=1">
<style>
.dropbtn {
background-color: #3498DB;
color: white;
padding: 16px;
font-size: 16px;
border: none;
cursor: pointer;
}
.dropbtn:hover, .dropbtn:focus {
background-color: #2980B9;
}
.dropdown {
position: relative;
display: inline-block;
}
.dropdown-content {
display: none;
position: absolute;
background-color: #f1f1f1;
min-width: 160px;
overflow: auto;
box-shadow: 0px 8px 16px 0px rgba(0,0,0,0.2);
z-index: 1;
}
.dropdown-content a {
color: black;
padding: 12px 16px;
text-decoration: none;
display: block;
}
.dropdown a:hover {background-color: #ddd;}
.show {display: block;}
</style>
</head>
<body>
<h2>Clickable Dropdown</h2>
<p>Click on the button to open the dropdown menu.</p>
<div class="dropdown">
<button onclick="myFunction()" class="dropbtn"><i class="fa fa-list-ul fa-3x"></i></button>
<div id="myDropdown" class="dropdown-content">
<a href="#home">Home</a>
<a href="#about">About</a>
<a href="#contact">Contact</a>
</div>
</div>
<script>
/* When the user clicks on the button,
toggle between hiding and showing the dropdown content */
function myFunction() {
document.getElementById("myDropdown").classList.toggle("show");
}
// Close the dropdown if the user clicks outside of it
window.onclick = function(event) {
if (!event.target.matches('.dropbtn')) {
var dropdowns = document.getElementsByClassName("dropdown-content");
var i;
for (i = 0; i < dropdowns.length; i++) {
var openDropdown = dropdowns[i];
if (openDropdown.classList.contains('show')) {
openDropdown.classList.remove('show');
}
}
}
}
</script>
</body>
</html>
事实证明，所遇到的问题很容易解决。只需添加一个空格，然后将.dropbtn类添加到已经存在的图标类中。另外，您将需要摆脱fa-3x部分。这是添加的类成员，用于使列表图标变大。但是，您也可以使用font =“ 3em的font =”“来做到这一点。
完成后，看起来应该像这样：
<i style="font-size: 3em;" class="fa fa-list-ul dropbtn"></i>