.nav-link:active {
color: #f00;
}
.text-success:active {
color: #f00;
} <html>
<head>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<link rel="stylesheet" type="text/css" href="css/bootstrap-4.1.0.min.css">
<link rel="stylesheet" type="text/css" href="css/index.css">
<title></title>
</head>
<body class="bg-dark">
<header>
<nav class="container-fluid navbar navbar-expand-md navbar-light bg-white my-3 rounded">
<a class="navbar-brand" href="#home"><img src="img/logo.png" class="img-responsive"></a>
<div class="navbar-nav ml-auto">
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNav" aria-expanded="false" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
</div>
<div class="collapse navbar-collapse" id="navbarNav">
<ul class="nav navbar-nav ml-auto">
<li class="nav-item"><a class="nav-link text-success font-weight-bold" href="#home">Home</a></li>
<li class="nav-item"><a class="nav-link text-success font-weight-bold" href="#about">About</a></li>
<li class="nav-item"><a class="nav-link text-success font-weight-bold" href="#quality">Quality</a></li>
<li class="nav-item"><a class="nav-link text-success font-weight-bold" href="#partners">Partners</a></li>
<li class="nav-item"><a class="nav-link text-success font-weight-bold" href="#contacts">Contacts</a></li>
</ul>
</div>
</nav>
</header>
<footer>
<p align="center" style="color: #fff">FOOTER</p>
</footer>
<script type="text/javascript" src="js/jquery-3.3.1.min.js"></script>
<script type="text/javascript" src="js/popper-1.14.3.min.js"></script>
<script type="text/javascript" src="js/bootstrap-4.1.0.min.js"></script>
</body>
</html>
问题是：