在默认的Bootstrap导航栏中为活动链接添加灰色背景色
要将灰色背景色添加到活动链接，请使用Bootstrap中的.active类。
您可以尝试运行以下代码来实现.active类-
示例
<!DOCTYPE html>
<html>
<head>
<title>Bootstrap Example</title>
<link href = "/bootstrap/css/bootstrap.min.css" rel = "stylesheet">
<script src = "/scripts/jquery.min.js"></script>
<script src = "/bootstrap/js/bootstrap.min.js"></script>
</head>
<body>
<nav class = "navbar navbar-default">
<div class = "container-fluid">
<div class = "navbar-header">
<a class = "navbar-brand" href = "#">Website</a>
</div>
<ul class = "nav navbar-nav">
<li class = "active"><a href = "#">Home</a></li>
<li><a href = "#">Tutorials</a></li>
<li><a href = "#">Quiz</a></li>
</ul>
</div>
</nav>
<div class = "container">
<h3>Demo</h3>
<p>This is demo text.</p>
</div>
</body>
</html>