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html - 使用引导程序居中

问题描述

我一直在使用引导程序，现在我在将我创建的东西居中时遇到了一些麻烦，第一个问题是无法垂直居中右侧导航栏项目，它只是位于导航栏的中心线上方，第二个是一个登录表单，包含在具有不同类的div中，我一直试图使其水平居中，为什么导航栏的右侧项目必须在左侧显示无序列表的点项目不显示，它只是改变了 div 的类。如果可能的话，我想在这方面得到一些帮助。

图片 这里的代码：

<!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>

标签： htmlcssbootstrap-4

解决方案

问题是你在 navbar-collapse 上使用了两个 ul，尝试只使用一个 ul，然后li用 property添加一个空的flex: 1，这个空的 li 将增长以填充元素之间的空间，将它们推到两侧。

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