<!DOCTYPE HTML><html><head><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>带表单的导航条</title><link rel="stylesheet" href="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/css/bootstrap.min.css"></head><body><!--代码--> <div class="navbar navbar-default"> <div class="navbar-header"> <a href="##" class="navbar-brand">慕课网</a> </div> <ul class="nav navbar-nav"> <li class="active"><a href="#">网站首页</a></li> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">名师介绍<span class="caret"></span></a> <ul class="dropdown-menu"> <li><a href="#">a</a></li> <li><a href="#">a</a></li> <li class="disabled"><a href="#">a</a></li> </ul> </li> <li><a href="#">成功案例</a></li> <li><a href="#">成功案例</a></li> <li><a href="#">关于我们</a></li> </ul> <form class="navbar-form navbar-right"> <div class="form-group"> <input type="text" class="form-control" placeholder="请输入关键词"> </div> <button type="submit" class="btn btn-default">搜索</button> </form></div><div class="navbar navbar-default" role="navigation"> <div class="navbar-header"> <a href="##" class="navbar-brand">慕课网</a> </div> <ul class="nav navbar-nav"> <li class="active"><a href="##">网站首页</a></li> <li class="dropdown"> <a href="##" data-toggle="dropdown" class="dropdown-toggle">系列教程<span class="caret"></span></a> <ul class="dropdown-menu"> <li><a href="##">CSS3</a></li> <li><a href="##">JavaScript</a></li> <li class="disabled"><a href="##">PHP</a></li> </ul> </li> <li><a href="##">名师介绍</a></li> <li><a href="##">成功案例</a></li> <li><a href="##">关于我们</a></li> </ul> <form action="##" class="navbar-form navbar-left" rol="search"> <div class="form-group"> <input type="text" class="form-control" placeholder="请输入关键词" /> </div> <button type="submit" class="btn btn-default">搜索</button> </form></div><script src="https://www.imooc.com/static/lib/jquery/1.9.1/jquery.js"></script><script src="//maxcdn.bootstrapcdn.com/bootstrap/3.2.0/js/bootstrap.min.js"></script> </body></html>
没听太懂问题，只知道.navbar-brand设置的字体是18px