<link href="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/css/bootstrap.min.css" rel="stylesheet" id="bootstrap-css">
<script src="//maxcdn.bootstrapcdn.com/bootstrap/4.1.1/js/bootstrap.min.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/3.2.1/jquery.min.js"></script>
<div class="header">
</div>
<div class="header_color">
<ul>
<li onclick="ColorChange('#f00');">Red</li>
<li onclick="ColorChange('green');">green</li>
<li onclick="ColorChange('blue');">blue</li>
</ul>
</div>
