如何在几个cols和整个屏幕上制作Bootstrap 4下拉菜单？

Question

如何在几个cols和整个屏幕上制作Bootstrap 4下拉菜单：

基本上，我希望有几个列的下拉菜单，并且是整个容器的宽度。 如何做到这一点？

＆＃13;

＆＃13;

#mainmenu {
  font-size: 1.1rem;
  background-color: #e3f2fd;
}

.dropdown-menu {
  min-width: 200px;
}

.dropdown-menu.columns-2 {
  min-width: 400px;
}

.dropdown-menu.columns-3 {
  min-width: 600px;
}

.dropdown-menu li a {
  padding: 5px 15px;
  font-weight: 300;
}

.multi-column-dropdown {
  list-style: none;
}

.multi-column-dropdown li a {
  display: block;
  clear: both;
  line-height: 1.428571429;
  color: #333;
  white-space: normal;
}

.multi-column-dropdown li a:hover {
  text-decoration: none;
  color: #262626;
  background-color: #f5f5f5;
}

@media (max-width: 767px) {
  .dropdown-menu.multi-column {
    min-width: 240px !important;
    overflow-x: hidden;
  }
}

＆＃13;

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">

<script src="https://code.jquery.com/jquery-3.2.1.slim.min.js" integrity="sha384-KJ3o2DKtIkvYIK3UENzmM7KCkRr/rE9/Qpg6aAZGJwFDMVNA/GpGFF93hXpG5KkN" crossorigin="anonymous"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/popper.js/1.12.9/umd/popper.min.js" integrity="sha384-ApNbgh9B+Y1QKtv3Rn7W3mgPxhU9K/ScQsAP7hUibX39j7fakFPskvXusvfa0b4Q" crossorigin="anonymous"></script>
<script src="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/js/bootstrap.min.js" integrity="sha384-JZR6Spejh4U02d8jOt6vLEHfe/JQGiRRSQQxSfFWpi1MquVdAyjUar5+76PVCmYl" crossorigin="anonymous"></script>


<nav id="mainmenu" class="navbar navbar-expand-md navbar-light bg-light ">

  <a id="" class="navbar-brand invisible" href="#">Action</a>

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

  <div class="collapse navbar-collapse justify-content-end" id="mainNavbar">
    <ul class="navbar-nav">
      <li class="nav-item active">
        <a class="nav-link" href="#">Action</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Action</a>
      </li>

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

        <ul class="dropdown-menu multi-column columns-3 ">
          <div class="row">
            <div class="col-sm-4">
              <ul class="multi-column-dropdown">
                <li>
                  <a href="#">
                    <h5>Action</h5>
                  </a>
                </li>
                <div class="dropdown-divider"></div>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
                <li class="divider"></li>
                <li><a href="#">One more separated link</a></li>
              </ul>
            </div>
            <div class="col-sm-4">
              <ul class="multi-column-dropdown">
                <li><a href="#">Action</a></li>
                <div class="dropdown-divider"></div>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
                <li class="divider"></li>
                <li><a href="#">One more separated link</a></li>
              </ul>
            </div>
            <div class="col-sm-4">
              <ul class="multi-column-dropdown">
                <li><a href="#">Action</a></li>
                <div class="dropdown-divider"></div>
                <li><a href="#">Another action</a></li>
                <li><a href="#">Something else here</a></li>
                <li class="divider"></li>
                <li><a href="#">Separated link</a></li>
                <li class="divider"></li>
                <li><a href="#">One more separated link</a></li>
              </ul>
            </div>
          </div>
        </ul>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Action</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Action</a>
      </li>
      <li class="nav-item">
        <a class="nav-link" href="#">Action</a>
      </li>
    </ul>
  </div>
</nav>

＆＃13;

＆＃13;

＆＃13;

这是我得到的。 基本上，我想要有几个列的下拉菜单，并且是整个容器的宽度。 如何做到这一点？

Answer 1

给父母一个静态位置：

<li class="nav-item dropdown has-megamenu">

的CSS：

.dropdown.has-megamenu{
position:static;
}

别忘了把你的一排列放在一个.container-fluid分类div中：

<div class="container-fluid"> <div class="row">