我一直在使用bootstrap,现在我正在创建的东西在居中时遇到了一些问题,第一个问题是无法垂直居中右侧导航栏项目,它只是在导航栏的中心线上方,第二个问题是一个包含不同类的div形式的日志,我一直试图使它水平居中,为什么导航栏的右侧项目必须在无序列表中显示一个点,而左侧的项目没有显示,它只是更改了div的类。如果可能的话,我想在这方面得到一些帮助。

代码如下:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Member area</title>
<link rel="stylesheet" href="style.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.2.0/css/all.css" integrity="sha384-hWVjflwFxL6sNzntih27bfxkr27PmbbK/iSvJ+a4+0owXq79v+lsFkW54bOGbiDQ" crossorigin="anonymous">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
</head>
<body>
<!-- NAV BAR -->
<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
<a class="navbar-brand" href="#">PlaceHolder</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="#">Home
<span class="sr-only">(current)</span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">About me</a>
</li>
</ul>
<ul class "navbar-nav ml-auto">
<li class="nav-item">
<a class="nav-link" href="#">Member Area</a>
</li>
</ul>
</div>
</nav>
<!--END OF NAV BAR-->
<!-- LOG IN FORM-->
<form action="">
<div class="form-group row">
<div class="container text-center">
<div class="ocol-lg-4 col-lg-offset-4">
<div class="col-3">
<label for="username">Username</label>
<input type="username" class="form-control" id="username" placeholder="Enter username">
</div>
<div class="col-3">
<label for="password">Password</label>
<input type="password" class="form-control" id="password" placeholder="Enter password">
</div>
<div class="col-3">
<input type="submit" class="form-control" id="submit" value="Submit">
</div>
</div>
</div>
</div>
</form>
<!-- END OF LOGIN FORM-->
</body>
</html>
发布于 2018-08-05 14:27:46
您的模板中存在许多问题。
首先,在<ul class "navbar-nav ml-auto">中的类属性后面缺少"=“符号
使用offset-lg-4而不是col-lg-offset-4
应该在container元素内部使用“div”,因此更改了容器div的位置。
从container元素中删除文本中心
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Member area</title>
<link rel="stylesheet" href="style.css">
<script src="https://code.jquery.com/jquery-3.3.1.slim.min.js" integrity="sha384-q8i/X+965DzO0rT7abK41JStQIAqVgRVzpbzo5smXKp4YfRvH+8abtTE1Pi6jizo" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.3/umd/popper.min.js" integrity="sha384-ZMP7rVo3mIykV+2+9J3UJ46jBk0WLaUAdn689aCwoqbBJiSnjAK/l8WvCWPIPm49" crossorigin="anonymous"></script>
<script src="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/js/bootstrap.min.js" integrity="sha384-ChfqqxuZUCnJSK3+MXmPNIyE6ZbWh2IMqE241rYiqJxyMiZ6OW/JmZQ5stwEULTy" crossorigin="anonymous"></script>
<link rel="stylesheet" href="https://use.fontawesome.com/releases/v5.2.0/css/all.css" integrity="sha384-hWVjflwFxL6sNzntih27bfxkr27PmbbK/iSvJ+a4+0owXq79v+lsFkW54bOGbiDQ" crossorigin="anonymous">
<link rel="stylesheet" href="https://stackpath.bootstrapcdn.com/bootstrap/4.1.3/css/bootstrap.min.css" integrity="sha384-MCw98/SFnGE8fJT3GXwEOngsV7Zt27NXFoaoApmYm81iuXoPkFOJwJ8ERdknLPMO" crossorigin="anonymous">
</head>
<body>
<!-- NAV BAR -->
<nav class="navbar navbar-expand-lg navbar-dark bg-dark">
<a class="navbar-brand" href="#">PlaceHolder</a>
<button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>
<div class="collapse navbar-collapse" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link" href="#">Home
<span class="sr-only">(current)</span>
</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">About me</a>
</li>
</ul>
<ul class="navbar-nav ml-auto">
<li class="nav-item">
<a class="nav-link" href="#">Member Area</a>
</li>
</ul>
</div>
</nav>
<!--END OF NAV BAR-->
<!-- LOG IN FORM-->
<div class="container">
<form action="">
<div class="form-group">
<div class="row">
<div class="col-lg-4 offset-lg-4 text-center">
<div class="">
<label for="username">Username</label>
<input type="username" class="form-control" id="username" placeholder="Enter username">
</div>
<div class="">
<label for="password">Password</label>
<input type="password" class="form-control" id="password" placeholder="Enter password">
</div>
<div class="">
<input type="submit" class="form-control" id="submit" value="Submit">
</div>
</div>
</div>
</div>
</form>
</div>
<!-- END OF LOGIN FORM-->
</body>
</html>
发布于 2018-08-05 14:03:16
问题是你正在使用两个ul,在navbar- space上,试着只使用一个ul,再添加一个带有flex: 1属性的空li,这个空的li会增长到填充元素之间的空间,把它们推到一边。
https://stackoverflow.com/questions/51691720
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