Question

我需要您的帮助

我是Web开发的初学者

您能解释一下为什么输入字段未对齐中心吗？

<"input type="text" id="search_bar" class="form-control" placeholder="Search" align="center">

在CSS中，我尝试在与输入字段相关的CSS的多个位置添加"float:center;"，但似乎根本没有任何作用。

这是代码：

<!DOCTYPE html>
<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">
<title>Bootstrap Navbar Dropdown Login and Signup Form with Social Buttons</title>
<link href="https://fonts.googleapis.com/css?family=Varela+Round" rel="stylesheet">
<link rel="stylesheet" href="https://fonts.googleapis.com/icon?family=Material+Icons">
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/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">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<style type="text/css">
	body{
		font-family: 'Varela Round', sans-serif;
		margin:0px;
	}
	.form-control {
		box-shadow: none;		
		font-weight: normal;
		font-size: 13px;
	}
	.form-control:focus {
		border-color: #33cabb;
		box-shadow: 0 0 8px rgba(0,0,0,0.1);
	}
	.navbar-header.col {
		padding: 0 !important;
	}	
	.navbar {
		background: #fff;
		height: 60px;
		padding-left: 10px;
		padding-right: 16px;
		border-radius: 0;
		box-shadow: 0 0px 0px 0 rgba(0, 0, 0, 0.2), 0 0px 0px 0 rgba(0, 0, 0, 0.19);
	}
	.nav-link img {
		border-radius: 50%;
		width: 36px;
		height: 36px;
		margin: -8px 0;
		float: left;
		margin-right: 10px;
	}
	.navbar .form-inline {
        display: inline-block;
    }
	.navbar .nav li {
		position: relative;
	}
	.navbar .nav li a {
		color: #888;
	}
	.search-box {
		float: center;
    }	
    .search-box input {
    	float: center;
		border-color: #dfe3e8;
        border-radius: 20px !important;
		box-shadow: none;
    }
	.search-box .input-group-addon {
		float: center;
        min-width: 35px;
        border: none;
        position: absolute;
        background: transparent;
        right: 0;
        z-index: 9;
        padding: 7px;
		height: 100%;
    }
    .search-box i {
        color: #a0a5b1;
		font-size: 19px;
    }
	.navbar .nav .btn-primary, .navbar .nav .btn-primary:active {
		color: #fff;
		background: #33cabb;
		padding-top: 8px;
		padding-bottom: 6px;
		vertical-align: middle;
		border: none;
	}	
	.navbar .nav .btn-primary:hover, .navbar .nav .btn-primary:focus {		
		color: #fff;
		outline: none;
		background: #31bfb1;
	}
	.navbar .navbar-right li:first-child a {
		padding-right: 30px;
	}
	.navbar .nav-item i {
		font-size: 18px;
	}
	.navbar .dropdown-item i {
		font-size: 16px;
		min-width: 22px;
	}
	.navbar ul.nav li.active a, .navbar ul.nav li.open > a {
		background: transparent !important;
	}	
	.navbar .nav .get-started-btn {
		min-width: 120px;
		margin-top: 8px;
		margin-bottom: 8px;
	}
	.navbar ul.nav li.open > a.get-started-btn {
		color: #fff;
		background: #31bfb1 !important;
	}
	.navbar .dropdown-menu {
		border-radius: 1px;
		border-color: #e5e5e5;
		box-shadow: 0 2px 8px rgba(0,0,0,.05);
	}
	.navbar .nav .dropdown-menu li {
		color: #999;
		font-weight: normal;
	}
	.navbar .nav .dropdown-menu li a, .navbar .nav .dropdown-menu li a:hover, .navbar .nav .dropdown-menu li a:focus {
		padding: 8px 20px;
		line-height: normal;
	}
	.navbar .navbar-form {
		border: none;
	}
	.navbar .dropdown-menu.form-wrapper {
		width: 280px;
		padding: 20px;
		left: auto;
		right: 0;
        font-size: 14px;
	}
	.navbar .dropdown-menu.form-wrapper a {		
		color: #33cabb;
		padding: 0 !important;
	}
	.navbar .dropdown-menu.form-wrapper a:hover{
		text-decoration: underline;
	}
	.navbar .form-wrapper .hint-text {
		text-align: center;
		margin-bottom: 15px;
		font-size: 13px;
	}
	.navbar .form-wrapper .social-btn .btn, .navbar .form-wrapper .social-btn .btn:hover {
		color: #fff;
        margin: 0;
		padding: 0 !important;
		font-size: 13px;
		border: none;
		transition: all 0.4s;
		text-align: center;
		line-height: 34px;
		width: 47%;
		text-decoration: none;
    }	
	.navbar .social-btn .btn-primary {
		background: #507cc0;
	}
	.navbar .social-btn .btn-primary:hover {
		background: #4676bd;
	}
	.navbar .social-btn .btn-info {
		background: #64ccf1;
	}
	.navbar .social-btn .btn-info:hover {
		background: #4ec7ef;
	}
	.navbar .social-btn .btn i {
		margin-right: 5px;
		font-size: 16px;
		position: relative;
		top: 2px;
	}
	.navbar .form-wrapper .form-footer {
		text-align: center;
		padding-top: 10px;
		font-size: 13px;
	}
	.navbar .form-wrapper .form-footer a:hover{
		text-decoration: underline;
	}
	.navbar .form-wrapper .checkbox-inline input {
		margin-top: 3px;
	}
	.or-seperator {
        margin-top: 32px;
		text-align: center;
		border-top: 1px solid #e0e0e0;
    }
    .or-seperator b {
		color: #666;
        padding: 0 8px;
		width: 30px;
		height: 30px;
		font-size: 13px;
		text-align: center;
		line-height: 26px;
		background: #fff;
		display: inline-block;
		border: 1px solid #e0e0e0;
		border-radius: 50%;
		position: relative;
		top: -15px;
		z-index: 1;
    }
    .navbar .checkbox-inline {
		font-size: 13px;
	}
	.navbar .navbar-right .dropdown-toggle::after {
		display: none;
	}
	@media (min-width: 1200px){
		.form-inline .input-group {
			width: 300px;
			margin-left: 30px;
		}
	}
	@media (max-width: 768px){
		.navbar .dropdown-menu.form-wrapper {
			width: 100%;
			padding: 10px 15px;
			background: transparent;
			border: none;
		}
		.navbar .form-inline {
			display: block;
		}
		.navbar .input-group {
			width: 100%;
		}
		.navbar .nav .btn-primary, .navbar .nav .btn-primary:active {
			display: block;
		}
	}
	.B{
		margin-top: 0px;
	height: 40px;
	width:65px;
	float: top;
	margin-top: 10px;
	display:inline-block;
}
.C{
	display:inline-block;
}
</style>
<script type="text/javascript">
	// Prevent dropdown menu from closing when click inside the form
	$(document).on("click", ".navbar-right .dropdown-menu", function(e){
		e.stopPropagation();
	});
</script>
</head> 
<body>
<nav class="navbar navbar-default navbar-expand-lg navbar-light">
	<div class="navbar-header d-flex col"><img src="logo.png" class="B" alt="logo"> 		
		<button type="button" data-target="#navbarCollapse" data-toggle="collapse" class="navbar-toggle navbar-toggler ml-auto">
			<span class="navbar-toggler-icon"></span>
			<span class="icon-bar"></span>
			<span class="icon-bar"></span>
			<span class="icon-bar"></span>
		</button>
	</div>
	<!-- Collection of nav links, forms, and other content for toggling -->
	<div id="navbarCollapse" class="collapse navbar-collapse justify-content-start">
		<form class="navbar-form form-inline">
			<div class="input-group search-box" align="center">								
				<input type="text" id="search_bar" class="form-control" placeholder="Search" align="center">
				<span class="input-group-addon"><i class="material-icons">&#xE8B6;</i></span>
			</div>
		</form>
		<ul class="nav navbar-nav navbar-right ml-auto">			
			<li class="nav-item">
				<a data-toggle="dropdown" class="nav-link dropdown-toggle" href="#">Login</a>
				<ul class="dropdown-menu form-wrapper">					
					<li>
						<form action="/examples/actions/confirmation.php" method="post">
							<p class="hint-text">Sign in with your social media account</p>
							<div class="form-group social-btn clearfix">
								<a href="#" class="btn btn-primary pull-left"><i class="fa fa-facebook"></i> Facebook</a>
								<a href="#" class="btn btn-info pull-right"><i class="fa fa-twitter"></i> Twitter</a>
							</div>
							<div class="or-seperator"><b>or</b></div>
							<div class="form-group">
								<input type="text" class="form-control" placeholder="Username" required="required">
							</div>
							<div class="form-group">
								<input type="password" class="form-control" placeholder="Password" required="required">
							</div>
							<input type="submit" class="btn btn-primary btn-block" value="Login">
							<div class="form-footer">
								<a href="#">Forgot Your password?</a>
							</div>
						</form>
					</li>
				</ul>
			</li>
			<li class="nav-item">
				<a href="#" data-toggle="dropdown" class="btn btn-primary dropdown-toggle get-started-btn mt-1 mb-1">Sign up</a>
				<ul class="dropdown-menu form-wrapper">					
					<li>
						<form action="/examples/actions/confirmation.php" method="post">
							<p class="hint-text">Fill in this form to create your account!</p>
							<div class="form-group">
								<input type="text" class="form-control" placeholder="Username" required="required">
							</div>
							<div class="form-group">
								<input type="password" class="form-control" placeholder="Password" required="required">
							</div>
							<div class="form-group">
								<input type="password" class="form-control" placeholder="Confirm Password" required="required">
							</div>
							<div class="form-group">
								<label class="checkbox-inline"><input type="checkbox" required="required"> I accept the <a href="#">Terms &amp; Conditions</a></label>
							</div>
							<input type="submit" class="btn btn-primary btn-block" value="Sign up">
						</form>
					</li>
				</ul>
			</li>
		</ul>
	</div>
</nav>
</body>
</html>

Answer 1

假设您希望在中心的输入字段中使用占位符。如果是这种情况，请尝试：

text-align: center;

Answer 2

只需将输入字段放在block元素内，并将该父元素设置为具有text-align:center;。

这样，您可以控制要相对于div（块元素）放置项目的位置

Answer 3

包含form元素的导航栏应将其子元素居中。

.navbarCollapse{
  text-align: center;
}

Answer 4

对标签使用不同的ID，对文本字段使用不同的ID。然后，您可以通过CSS轻松管理它们。

输入字段未居中对齐？

4 个答案: