如何在搜索引导程序4中将搜索栏置于屏幕中间（在页脚和导航之间水平和垂直）的中心，并使其对移动设备做出响应。
我尝试使用自定义样式强制它（没有引导程序）.centerd。
但是，当我这样做时，页脚在小型移动设备中位于搜索栏的顶部，并且似乎不是很敏感。
<!-- Initialize Bootstrap functionality -->
// Initialize tooltip component
$(function() {
$('[data-toggle="tooltip"]').tooltip()
})
// Initialize popover component
$(function() {
$('[data-toggle="popover"]').popover()
})/*
* Masthead for nav
*/
.blog-masthead {
background-color: #0275D8;
-webkit-box-shadow: inset 0 -2px 5px rgba(0, 0, 0, .1);
box-shadow: inset 0 -2px 5px rgba(0, 0, 0, .1);
}
/* Nav links */
.blog-nav-item {
position: relative;
display: inline-block;
padding: 10px;
font-weight: 500;
color: #fff;
}
.blog-nav-item:hover,
.blog-nav-item:focus {
color: #fff;
text-decoration: none;
}
/* Active state gets a caret at the bottom */
.blog-nav .active {
color: #fff;
}
.blog-nav .active:after {
position: absolute;
bottom: 0;
left: 50%;
width: 0;
height: 0;
margin-left: -5px;
vertical-align: middle;
content: " ";
border-right: 5px solid transparent;
border-bottom: 5px solid;
border-left: 5px solid transparent;
}
* {
border-radius: 0 !important;
}
* {
-webkit-border-radius: 0 !important;
-moz-border-radius: 0 !important;
border-radius: 0 !important;
}
/*
* Blog name and description
*/
/*
* Footer
*/
.blog-footer {
padding: 40px 0;
color: #999;
text-align: center;
background-color: #f9f9f9;
border-top: 1px solid #e5e5e5;
}
.blog-footer p:last-child {
margin-bottom: 0;
}
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: #0275D8;
}
a {
color: #f00;
}
a:hover {
color: #0f0;
}<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1, shrink-to-fit=no">
<meta name="description" content="">
<meta name="author" content="">
<link rel="icon" href="/favicon.ico">
<style type="text/css">
html,
body {
overflow-x: hidden;
}
.centeredd {
position: fixed;
top: 50%;
left: 50%;
/* bring your own prefixes */
transform: translate(-50%, -50%);
}
</style>
<title>Bootstrap 4 Template</title>
<link rel="stylesheet" href="Navigation Bar.css">
<link rel="stylesheet" href="Sticky Footer.css">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" crossorigin="anonymous">
</head>
<body>
<div class="blog-masthead col-xs-12">
<div class="container">
<nav class="blog-nav">
<a class="blog-nav-item active" href="#">Home</a>
<a class="blog-nav-item" href="#">New features</a>
<a class="blog-nav-item" href="#">Press</a>
<a class="blog-nav-item" href="#">New hires</a>
<a class="blog-nav-item" href="#">About</a>
</nav>
</div>
</div>
<div class="col-lg-6 mx-auto">
<div class="input-group">
<input type="text" class="form-control" placeholder="Search for...">
<span class="input-group-btn">
<button class="btn btn-secondary" type="button">Go!</button>
</span>
</div>
</div>
</div>
<footer class="footer">
<div class="container">
<span class="text">Place sticky footer content here.</span>
</div>
</footer>
<!-- Bootstrap core JavaScript
================================================== -->
<!-- Placed at the end of the document so the pages load faster -->
<!-- jQuery library -->
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.0.0/jquery.min.js" integrity="sha384-THPy051/pYDQGanwU6poAc/hOdQxjnOEXzbT+OuUAFqNqFjL+4IGLBgCJC3ZOShY" crossorigin="anonymous"></script>
<!-- Tether -->
<script src="https://cdnjs.cloudflare.com/ajax/libs/tether/1.2.0/js/tether.min.js" integrity="sha384-Plbmg8JY28KFelvJVai01l8WyZzrYWG825m+cZ0eDDS1f7d/js6ikvy1+X+guPIB" crossorigin="anonymous"></script>
<!-- Latest compiled JavaScript -->
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0-alpha.3/js/bootstrap.min.js" integrity="sha384-ux8v3A6CPtOTqOzMKiuo3d/DomGaaClxFYdCu2HPMBEkf6x2xiDyJ7gkXU0MWwaD" crossorigin="anonymous"></script>
</body>
</html>
答案 0 :(得分：1)
如何在搜索引导程序4中将搜索栏置于屏幕中间（在页脚和导航之间水平和垂直）的中心，并使其对移动设备做出响应。
要使搜索栏水平居中，您只需要有效的HTML（某些HTML当前无效），然后您需要将Bootstrap列放入Bootstrap行并将其放入Bootstrap容器中，如下所示：
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<div class="container">
<div class="row">
<div class="col-lg-6 mx-auto">
<div class="input-group">
<input type="text" class="form-control" placeholder="Search for...">
<span class="input-group-btn">
<button class="btn btn-secondary" type="button">Go!</button>
</span>
</div>
</div>
</div>
</div>
以水平和垂直为中心，您可以这样做：
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<div class="container">
<div class="blog-masthead">
<nav class="blog-nav">
<a class="blog-nav-item active" href="#">Home</a>
<a class="blog-nav-item" href="#">New features</a>
<a class="blog-nav-item" href="#">Press</a>
<a class="blog-nav-item" href="#">New hires</a>
<a class="blog-nav-item" href="#">About</a>
</nav>
</div>
<div class="row align-items-center" style="min-height: calc(100vh - 66px);">
<div class="col-lg-6 mx-auto">
<div class="input-group">
<input type="text" class="form-control" placeholder="Search for...">
<span class="input-group-btn">
<button class="btn btn-secondary" type="button">Go!</button>
</span>
</div>
</div>
</div>
<footer class="footer fixed-bottom text-center">
<span class="text">Place sticky footer content here.</span>
</footer>
</div>
因此，您将所有内容放在一个.container中，然后将style="min-height: calc(100vh - 66px);"之类的内容添加到主内容行以定义高度。
100vh表示100％视口高度，然后您减去标题/导航所占用的像素数（在本例中我使用了66px）。
align-items-center类垂直对齐内容。
页脚上的fixed-bottom会给你一个粘性页脚。