Here is the code:
<!DOCTYPE html>
<html>
<body>
<div data-role="tabs">
<div data-role="navbar">
<ul>
<li><a href="#tabone" >one</a></li>
<li><a href="#tabtwo">two</a></li>
</ul>
</div>
<div id="tabone" class="ui-content">
<h1>First tab contents</h1>
<a href="index.html" style="text-decoration: none"><button class="ui-btn ui-icon-arrow-l ui-btn-icon-left">Go back to page 1</button>
</a>
</div>
<div id="tabtwo" class="ui-content">
<h1>Second tab contents</h1>
</div>
</div>
</body>
I'm not sure what's going wrong with it, I've tried a couple different ways of arranging it but it just comes out like the image below. Any help would be greatly appreciated!

Consider the following example based on the Demo: https://jqueryui.com/tabs/