Problem with eirenaios answer:
When the drop-down menu is contained in a collapsible navigation bar, several <li> lines will be displayed on one line (until it is transferred to the next line) when the navigation bar is minimized. It looks very ugly and confusing.
Here is a solution based on eirenaios answer, but it also works for switchable (collapsible) navigators with drop-down menus:
https://plnkr.co/edit/JnsvKGiBokrI1frxC11P?p=preview
EDIT:Extra CSS rule:
.open > .dropdown-menu { display: table-caption; }
HTML (basically the same as the original, but surrounded by .navbar-collapse and added .navbar-header with a hamburger menu button to open a minimized menu):
<nav class="navbar navbar-default"> <div class="navbar-header" data-toggle="collapse" data-target="#navbar0"> <button type="button" class="navbar-toggle"> <span class="icon-bar"></span><span class="icon-bar"></span><span class="icon-bar"></span> </button> </div> <div class="collapse navbar-collapse" id="navbar0"> <ul class="nav navbar-nav"> <li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown" role="button" aria-haspopup="true" aria-expanded="false">Dropdown Menu A <span class="caret"></span></a> <ul class="dropdown-menu"> <li class="hz"> <a href="#">Item A1 left</a> <a href="#">Item A1 right</a> </li> <li class="hz"> <a href="#">Item A2 left</a> <a href="#">Item A2 right</a> </li> <li> <a href="#">Single item A3</a> </li> <li class="hz"> <a href="#">Item A3 left</a> <a href="#">Item A3 right</a> </li> </ul> </li> </ul> </div> </nav>
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