我尝试将此导航栏下拉菜单分成两列，但它们相互冲突。
另一个问题是，在移动设备上搜索栏保持在底部。并且页面没有响应。不知道是不是导航栏问题导致的。任何意见将不胜感激。希望大家周末愉快！
html {
position: relative;
min-height: 100%;
}
body {
margin-bottom: 60px;
}
section {
padding: 70px 0;
border-bottom: 1px dotted #ccc;
}
.grid-example div[class^="col"] {
border: 1px solid white;
background: lightblue;
text-align: center;
padding-top: 8px;
padding-bottom: 8px;
}
.jumbotron {
background-color: lightskyblue;
}
table th {
text-align: center;
}
.table {
margin: auto;
width: 50% !important;
}
.table td {
text-align: center;
}
.footer {
position: absolute;
bottom: 0;
width: 100%;
height: 60px;
line-height: 60px;
color: #fff;
text-align: center;
background-color: #C0C0C0;
}
a {
color: #f00;
}
a:hover {
color: #0f0;
}<!doctype html>
<html lang="en">
<head>
<!-- Required meta tags -->
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<title>Test</title>
<meta name="description" content="Test">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<!-- Bootstrap CSS -->
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<link rel="stylesheet" href="Sticky Footer.css">
</head>
<body>
<nav class="navbar-expand-sm navbar-expand-md navbar-expand-lg navbar navbar-light" style="background-color: #C0C0C0;">
<a class="navbar-brand" href="#">Navbar</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarNavDropdown">
<ul class="navbar-nav">
<li class="nav-item active">
<a class="nav-link" href="#">Test <span class="sr-only">(current)</span></a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Test</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Test</a>
</li>
<li class="nav-item dropdown">
<a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
Test
</a>
<div class="dropdown-menu" style="width:300px" aria-labelledby="navbarDropdown">
<div class="container container-sm">
<div class="row">
<div class="col-sm-4">
<a class="dropdown-item" href="#">Test Test Test</a>
<a class="dropdown-item" href="#">Test Test</a>
<a class="dropdown-item" href="#">Test</a>
</div>
<div class="col-sm-4">
<a class="dropdown-item" href="#">itemitemitemitem</a>
<a class="dropdown-item" href="#">itemitemitemitemitem</a>
<a class="dropdown-item" href="#">item</a>
</div>
</div>
</div>
</li>
</ul>
</div>
</nav>
<div class="jumbotron">
<h1 class="display-8">Hello, world!</h1>
<p class="lead-8">This is a simple hero unit, a simple jumbotron-style component for calling extra attention to featured content or information.</p>
<p class="lead">
<a class="btn btn-primary btn-md" href="#" role="button">Learn more</a>
</p>
</div>
<div class="row align-items-center" style="min-height: calc(100vh - 500px);">
<div class="col-xs-3 col-sm-8 col-md-6 col-lg-6 mx-auto">
<div class="input-group-prepend">
<input id='urlurl' type="url" class="form-control" placeholder="Search" pattern="https?://.+" required />
<span class="input-group-btn">
<button class="btn btn-primary" style="background-color: #0275D8; border-color: #0275D8;" type="button" >Test</button>
</span>
</div>
</div>
</div>
<footer class="footer fixed-bottom text-center">
<span class="text">Place sticky footer content here.</span>
</footer>
<!-- jQuery Version 1.11.1 -->
<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<!-- Bootstrap Core JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>
</body>
</html>我将回答标题附带的下拉问题。 您不想在下拉列表中嵌套
containermin-widthhttps://codeply.com/go/9wUCwUErKL
<div class="dropdown-menu" style="min-width:360px" aria-labelledby="navbarDropdown">
<div class="row no-gutters">
<div class="col-sm-6">
<a class="dropdown-item px-2" href="#">Test Test Test</a>
<a class="dropdown-item px-2" href="#">Test Test</a>
<a class="dropdown-item px-2" href="#">Test</a>
</div>
<div class="col-sm-6">
<a class="dropdown-item px-2" href="#">itemitemitemitem</a>
<a class="dropdown-item px-2" href="#">itemitemitemitemitem</a>
<a class="dropdown-item px-2" href="#">item</a>
</div>
</div>
</div>
Bootstrap 4 中不再有
col-xs-*col-*