After extensive research and testing, I have successfully resolved the issue mentioned above. Feel free to check out the demo link below:
DEMO
HTML
<ul class="nav nav-pills">
<li class="active"><a href="#">Regular link</a></li>
<li class="dropdown">
<a href="#" data-toggle="dropdown" class="dropdown-toggle">Dropdown <b class="caret"></b></a>
<ul class="dropdown-menu" id="menu1">
<li>
<a href="#">2-level Menu <i class="icon-arrow-right"></i></a>
<ul class="dropdown-menu sub-menu">
<li><a href="#">Action</a></li>
<li><a href="#">Another action</a></li>
<li><a href="#">Something else here</a></li>
<li class="divider"></li>
<li class="nav-header">Nav header</li>
<li><a href="#">Separated link</a></li>
<li><a href="#">One more separated link</a></li>
</ul>
</li>
<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>
</ul>
</li>
<li class="dropdown">
<a href="#">Menu</a>
</li>
<li class="dropdown">
<a href="#">Menu</a>
</li>
</ul>
CSS
.dropdown-menu .sub-menu {
left: 100%;
position: absolute;
top: 0;
visibility: hidden;
margin-top: -1px;
}
.dropdown-menu li:hover .sub-menu {
visibility: visible;
display: block;
}
.navbar .sub-menu:before {
border-bottom: 7px solid transparent;
border-left: none;
border-right: 7px solid rgba(0, 0, 0, 0.2);
border-top: 7px solid transparent;
left: -7px;
top: 10px;
}
.navbar .sub-menu:after {
border-top: 6px solid transparent;
border-left: none;
border-right: 6px solid #fff;
border-bottom: 6px solid transparent;
left: 10px;
top: 11px;
left: -6px;
}
DEMO