Html 导航栏不显示项目

在一个角度项目中，我创建了导航栏组件。这是navbar.html的上下文

<nav class="navbar navbar-toggleable-md navbar-light bg-white fixed-top mediumnavigation">
  <button class="navbar-toggler navbar-toggler-right" type="button" data-toggle="collapse" data-target="#navbarsExampleDefault" aria-controls="navbarsExampleDefault" aria-expanded="false" aria-label="Toggle navigation">
        <span class="navbar-toggler-icon"></span>
    </button>
  <div class="container">
    <!-- Begin Logo -->
    <a class="navbar-brand" routerLink="blog-detail" routerLinkActive="active">
      <img src="assets/img/logo.png" alt="logo" />
    </a>
    <!-- End Logo -->
    <div class="collapse navbar-collapse" id="navbarsExampleDefault">
      <!-- Begin Menu -->
      <ul class="navbar-nav ml-auto">
        <li class="nav-item active">
          <a class="nav-link">Stories</a>
        </li>
        <li class="nav-item">
          <a class="nav-link">Post</a>
        </li>
        <li class="nav-item">
          <a class="nav-link">Another</a>
        </li>
      </ul>
      <!-- End Menu -->
      <!-- Begin Search -->
      <form class="form-inline my-2 my-lg-0">
        <input class="form-control mr-sm-2" type="text" placeholder="Search" />
        <span class="search-icon"><svg class="svgIcon-use" width="25" height="25" viewbox="0 0 25 25">
                        <path
                            d="M20.067 18.933l-4.157-4.157a6 6 0 1 0-.884.884l4.157 4.157a.624.624 0 1 0 .884-.884zM6.5 11c0-2.62 2.13-4.75 4.75-4.75S16 8.38 16 11s-2.13 4.75-4.75 4.75S6.5 13.62 6.5 11z">
                        </path>
                    </svg>
                </span>
      </form>
      <!-- End Search -->
    </div>
  </div>
</nav>
<!-- End Nav

故事


邮递


另一个


尝试添加以下类别：

navbar-expand-lg


到

<nav> 



html标记，如下所示：

<nav class="navbar navbar-expand-lg navbar-toggleable-md navbar-light bg-white fixed-top mediumnavigation">



如果这解决了问题，原因可能是您没有告诉折叠的html元素为此特定屏幕大小展开。
Thank。你，詹姆斯，成功了：）
<nav class="navbar navbar-expand-lg navbar-toggleable-md navbar-light bg-white fixed-top mediumnavigation">