The Bootstrap (v3.x) navbar example can be find here: http://getbootstrap.com/components/#navbar
Use the Pills verson as the base:
<ul class="nav nav-pills" id="topMenu">
...
<li role="presentation" class="dropdown">
<a class="dropdown-toggle" data-toggle="dropdown" href="#" role="button" aria-haspopup="true" aria-expanded="false">
Dropdown <span class="caret"></span>
</a>
<ul class="dropdown-menu">
...
</ul>
</li>
...
</ul>
This an Id for css:
#topMenu > li.active,
#topMenu > li.active :focus {
border-bottom: 4px solid #ff9900;
margin-bottom: -4px;
}#topMenu >li.active :hover { /*ensure hover not change to ligthgray if it's the activeLine'*/
border-bottom: 4px solid #ff9900;
margin-bottom: -4px;
}#topMenu > li:hover,
#topMenu > li:focus {
background-color: transparent;
border-bottom: 4px solid lightgray;
margin-bottom: -4px;
-ms-border-radius: 0;
border-radius: 0;
}#topMenu > li > a {
padding-bottom: 0;
color: #337ab7;
background-color: transparent;
}