JSFiddle - React, Tailwind, and code Playground
HTML
<script src="http://netdna.bootstrapcdn.com/bootstrap/3.0.0-rc1/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://netdna.bootstrapcdn.com/bootstrap/3.0.0-rc1/css/bootstrap.min.css">
<nav class="navbar navbar-default navbar-static-top" role="navigation">
<ul class="nav navbar-nav">
<li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">List Item1</a>
<ul class="dropdown-menu" id='Numberlist'>
<ul class='list-inline'>
<li><a href="#" id="">1</a></li>
<li><a href="#" id="">2</a></li>
<li><a href="#" id="">1</a></li>
<li><a href="#" id="">2</a></li>
<li><a href="#" id="">3</a></li>
<li><a href="#" id="">4</a></li>
<li><a href="#" id="">5</a></li>
<li><a href="#" id="">6</a></li>
</ul>
</ul>
</li>
<li class="dropdown"> <a href="#" class="dropdown-toggle" data-toggle="dropdown">List Item2</a>
<ul class="dropdown-menu" >
<ul class='list-inline'>
<li><a href="#" id="">1</a></li>
<li><a href="#" id="">2</a></li>
<li><a href="#" id="">1</a></li>
<li><a href="#" id="">2</a></li>
<li><a href="#" id="">3</a></li>
<li><a href="#" id="">4</a></li>
<li><a href="#" id="">5</a></li>
<li><a href="#" id="">6</a></li>
</ul>
</ul>
</li>
</ul>
</nav>
CSS
#Numberlist.dropdown-menu{
min-width: 200px;
}