双行引导程序 4 导航栏的问题

Question

我一直在尝试创建两个引导导航栏。第一个在中心有网站域名，有一个下拉菜单可以转到其他部分。然后每个部分都有自己的子栏和自己的链接。

目前看起来像这样。

这很棒，正是我想要的。但是，当我单击品牌名称的下拉菜单时，它会被推到左侧并与另一个导航栏重叠。

我还想将我的主题选择器和用户配置文件下拉到顶部导航栏，与屏幕右侧对齐。但是每次我尝试它只会破坏顶部导航栏，并且用户配置文件下拉列表会出现相同的重叠问题。

<nav id="topnav" class="navbar navbar-expand-lg navbar-dark bg-primary">
       <a class="navbar-brand dropdown-toggle ml-auto mr-auto" href="#navbarDropdown" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">WebsiteName</a>
      <div class="dropdown-menu" id="navbarDropdown" aria-labelledby="navbarDropdown">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <div class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Something else here</a>
    </div>

  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navcollapse" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
</button>
</nav>

     <nav id ="bottomnav" class="navbar navbar-expand-lg navbar-dark bg-primary py-0 sticky-top">
<div class="container">
  <div id="navcollapse" class="collapse navbar-collapse my-2">
        <ul class="navbar-nav mr-auto">
          <li class="nav-item">
            <a class="nav-link" href="/">Section Home</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="/Section/">Section</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="/Section/">Section</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="/Section/">Section</a>
          </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
              Section Dropdown
            </a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdown">
              <a class="dropdown-item" href="/Section/">Section</a>
              <a class="dropdown-item" href="/Section/">Section</a>
              <a class="dropdown-item" href="/Section/">Section</a>
            </div>
          </li>
        </ul>
        <ul class="navbar-nav ml-auto">
          <li class="nav-item">
            <a class="nav-link" href="#" data-toggle="modal" data-target="#themeModal"><i class="fas fa-moon fa-white"></i></a>

      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Username
        </a>

        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
             <a class="dropdown-item" href="/profile/">Profile</a>
            <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="/section/">section</a>

        <div class="dropdown-divider"></div>
         <a class="dropdown-item" href="/logout/">Logout</a>
        </div>
      </li>
        </ul>
        <form class="form-inline my-2 my-lg-0" action="/search">
          <input class="form-control mr-sm-2" type="text" name="q" placeholder="Search">
        </form>
</div>
</div>

Answer 1

添加

div.dropdown-menu{
left: 50%;
transform: translateX(-50%);
 z-index: 9999;
}

把它放在中心。默认情况下，引导程序具有left:0，因此它显示在a 的左侧。 z-index: 9999 因为带有sticky-top 类的导航栏有z-index: 1020;

https://codepen.io/Xenio/pen/LqmamQ888

div.dropdown-menu{
left: 50%;
transform: translateX(-50%);
 z-index: 9999;
}

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.2.1/css/bootstrap.min.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.14.6/umd/popper.min.js"></script>
  <script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.2.1/js/bootstrap.min.js"></script>
<nav id="topnav" class="navbar navbar-expand-lg navbar-dark bg-primary">
       <a class="navbar-brand dropdown-toggle ml-auto mr-auto" href="#navbarDropdown" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">WebsiteName</a>
      <div class="dropdown-menu" id="navbarDropdown" aria-labelledby="navbarDropdown">
      <a class="dropdown-item" href="#">Action</a>
      <a class="dropdown-item" href="#">Another action</a>
      <div class="dropdown-divider"></div>
      <a class="dropdown-item" href="#">Something else here</a>
    </div>

  <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navcollapse" aria-controls="navbarNav" aria-expanded="false" aria-label="Toggle navigation">
    <span class="navbar-toggler-icon"></span>
</button>
</nav>

     <nav id ="bottomnav" class="navbar navbar-expand-lg navbar-dark bg-primary py-0 sticky-top">
<div class="container">
  <div id="navcollapse" class="collapse navbar-collapse my-2">
        <ul class="navbar-nav mr-auto">
          <li class="nav-item">
            <a class="nav-link" href="/">Section Home</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="/Section/">Section</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="/Section/">Section</a>
          </li>
          <li class="nav-item">
            <a class="nav-link" href="/Section/">Section</a>
          </li>
          <li class="nav-item dropdown">
            <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
              Section Dropdown
            </a>
            <div class="dropdown-menu" aria-labelledby="navbarDropdown">
              <a class="dropdown-item" href="/Section/">Section</a>
              <a class="dropdown-item" href="/Section/">Section</a>
              <a class="dropdown-item" href="/Section/">Section</a>
            </div>
          </li>
        </ul>
        <ul class="navbar-nav ml-auto">
          <li class="nav-item">
            <a class="nav-link" href="#" data-toggle="modal" data-target="#themeModal"><i class="fas fa-moon fa-white"></i></a>

      <li class="nav-item dropdown">
        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
          Username
        </a>

        <div class="dropdown-menu" aria-labelledby="navbarDropdown">
             <a class="dropdown-item" href="/profile/">Profile</a>
            <div class="dropdown-divider"></div>
          <a class="dropdown-item" href="/section/">section</a>

        <div class="dropdown-divider"></div>
         <a class="dropdown-item" href="/logout/">Logout</a>
        </div>
      </li>
        </ul>
        <form class="form-inline my-2 my-lg-0" action="/search">
          <input class="form-control mr-sm-2" type="text" name="q" placeholder="Search">
        </form>
</div>
</div>