【发布时间】：2017-03-05 11:21:38
【问题描述】：
这是我的codepen.
问题 1
如何更改网页上导航栏下拉菜单的背景和文本颜色？仅出于回答目的，我希望文本为白色，背景颜色为灰色。 （我不是要求任何人为我做这件事，只是想把事情说清楚）
问题 2
在我的编码中，当我将鼠标悬停在框底部下拉菜单中的导航栏文本上时，会出现下划线。但是，我希望当用户将鼠标悬停在每个网页的每个文本下方而不是导航栏下拉菜单框的底部时，下划线会出现在每个网页的每个文本下方。
任何与识别类有关的有用链接？
此外，就导航栏 html 而言，我发现很难识别类名来做什么，因此，当我编写 CSS 时，我可以很容易地识别出我需要编写的类。因此，我想知道是否有人有任何有用的教程链接可以帮助我。
HTML 代码
<html>
<head>
<title>Liam Docherty | London Web Developer & GFX designer</title>
<link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">
</head>
<body>
<nav class="navbar navbar-default">
<div class="container-fluid">
<!-- Brand and toggle get grouped for better mobile display -->
<div class="navbar-header">
<button type="button" class="navbar-toggle collapsed" data-toggle="collapse" data-target="#bs-example-navbar-collapse-1" aria-expanded="false">
<span class="sr-only">Toggle navigation</span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</button>
<a class="navbar-brand" href="#"><img src="http://placehold.it/60x60" alt="Your Brand Name"></a>
</div>
<!-- Collect the nav links, forms, and other content for toggling -->
<div class="collapse navbar-collapse" id="bs-example-navbar-collapse-1">
<ul class="nav navbar-nav">
<li><a href="#">Home</a>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="true">About Me <span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="#">Action</a>
</li>
<li><a href="#">Another action</a>
</li>
<li><a href="#">Something else here</a>
</li>
<li role="separator" class="divider"></li>
<li><a href="#">Separated link</a>
</li>
<li role="separator" class="divider"></li>
<li><a href="#">One more separated link</a>
</li>
</ul>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Units <span class="caret"></span></a>
<ul class="dropdown-menu">
<li><a href="#">Action</a>
</li>
<li><a href="#">Another action</a>
</li>
<li><a href="#">Something else here</a>
</li>
<li role="separator" class="divider"></li>
<li><a href="#">Separated link</a>
</li>
<li role="separator" class="divider"></li>
<li><a href="#">One more separated link</a>
</li>
</ul>
</li>
<li><a href="#">Clients</a>
</li>
<li><a href="#contact-me">Contact Me</a>
</li>
</ul>
</div><!-- /.navbar-collapse -->
</div><!-- /.container-fluid -->
</nav>
<section class="section1">
<div class="hero"></div>
<a href= "#section2"><i class="fa fa-angle-down" style="font-size:100px;"></i></a>
</section>
<section class="section2" id = "section2">
<a href = "#contact-me"> <i class="fa fa-angle-down" style="font-size:100px;"></i></a>
</section>
<section id="contact-me" class="contact_section">
</section>
<script src="https://code.jquery.com/jquery-3.1.1.js" integrity="sha256-16cdPddA6VdVInumRGo6IbivbERE8p7CQR3HzTBuELA=" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
</body>
<footer></footer>
</html>
CSS 代码
<style>
body {
margin: 0;
padding: 0;
}
.navbar.navbar-default {
background-color: #4D5061;
height: 10vh;
}
.navbar.navbar-default ul {
list-style-type: none;
text-align: center;
}
.navbar.navbar-default ul li {
display: inline-block;
}
.navbar.navbar-default ul li a {
display: inline-block;
padding: 3.5vh 8px 4px;
color: white;
text-decoration: none;
font-size: 14pt;
font-family: 'Roboto', sans-serif;
}
.navbar.navbar-default ul li:after {
content: '';
position: absolute;
right: 50%;
bottom: 0;
left: 50%;
height: 3px;
background-color:red;
border-radius: 9px;
transition:all .2s;
}
.navbar.navbar-default ul li a:hover {
color: red;
}
.nav.navbar-nav, .nav.navbar-nav>li {
float: none;
}
.navbar.navbar-default ul li:hover:after {
right: 0;
left: 0;
}
a:hover {
color:red;
text-decoration:none;
}
#logo {
padding-top: 2vh;
padding-left: 20px;
float: left;
}
section {
position: relative;
}
.section1 {
height: 90vh;
background-color: #FFFFFF;
text-align: center;
}
.section2 {
height: 95vh;
background-color: #A59E8C;
text-align: center;
color: white;
}
.contact_section {
height: 93vh;
background-color: grey;
}
.fa-angle-down {
color: #4D5061;
position: absolute;
bottom: 0px;
}
footer {
height: 5vh;
}
</style>
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