调整大小时导航栏消失

Question

当网页收缩时，我的导航栏会消失，即使在页面收缩时单击切换开关也根本不会显示链接。我正在使用bootstrap 4.0并链接到cdn链接对于css和其他需要的JavaScript，它一直在消失。

<nav class="navbar navbar-expand-lg navbar-light bg-light" id="navbar">
<div class="container-fluid">
<button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarSupportedContent" aria-controls="navbarSupportedContent" aria-expanded="false" aria-label="Toggle navigation">
<span class="navbar-toggler-icon"></span>
</button>

<div class="collapse navbar-collapse ml-2 top-bar" id="navbarSupportedContent">
<ul class="navbar-nav mr-auto">
<li class="nav-item">
<a class="nav-link active" aria-current="page" href="#">Home </a>
</li>
<li class="nav-item collections">
<a class="nav-link collections" href="#">Services</a>
<ul class="dropdown-menu dropdown-firstmenu">
<li class="dropdown-submenu">
<a tabindex="-1" href="#">2014 <span class="dropdown-caret"><i class="fa fa-caret-right"></i></span></a>
</li>
<li class="dropdown-submenu">
<a tabindex="-1" href="#">2014 <span class="dropdown-caret"><i class="fa fa-caret-right"></i></span></a>
</li>
<li class="dropdown-submenu">
<a tabindex="-1" href="#">2014 <span class="dropdown-caret"><i class="fa fa-caret-right"></i></span></a>
</li>
<li class="dropdown-submenu">
<a tabindex="-1" href="#">2014 <span class="dropdown-caret"><i class="fa fa-caret-right"></i></span></a>
</li>
</ul>
</li>
<li class="nav-item collections">
<a class="nav-link collections" href="#">Products</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Support</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Downloads</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Blog</a>
</li>
<!-- drop down -->
<li class="nav-item collections">
<a class="nav-link collections" href="#">About</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#">Contact</a>
</li>
<!-- end drop down -->
</ul>
<ul class="navbar-nav ">
<li class="nav-item">
<a class="nav-link" href="#">My Account</a>
</li>
</ul>

Answer 1

我可以通过下载bootstrap 4.0 css并将导航栏显示从display:none更改为display:block来解决此问题