Twitter bootstrap 折叠汉堡包菜单在bootstrap 4'中不可见；什么是导航条反向？

我想将导航栏设置为反向颜色；然而，除了汉堡包菜单外，navbar品牌和nav项目也在展示中。当我将其更改为导航栏黑色时，汉堡菜单再次可见。这是什么原因

<nav class="navbar navbar-expand-lg navbar-inverse">
    <a id="logo" class="navbar-brand" href="/">Logo</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 justify-content-start" id="navbarSupportedContent">
        <ul class="navbar-nav">
            <li class="nav-item">
                <a class="nav-link text-light" href="#">Browse</a>
            </li>
        </ul>
    </div>
</nav>

引导程序4与引导程序3相比有重大变化。
我用它从BS3升级到BS4
这是您的Bs4黑色导航栏

<nav class="navbar navbar-expand-lg navbar-dark bg-dark navbar-expand-md"> <a id="logo" class="navbar-brand" href="/">Logo</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 justify-content-start" id="navbarSupportedContent">
    <ul class="navbar-nav">
        <li class="nav-item"> <a class="nav-link text-light" href="#">Browse</a>
        </li>
    </ul>
</div>

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因为引导4 alpha后，导航栏反转变为导航栏暗