How to change button alignment code example

Example 1: how to make a button centered in html5

<!--Put the button inside a p like this-->
<p style="text-align: center;"><button>See?</button>Whatever</p>

Example 2: how to right align a text button

<h1>Button with Text</h1>
<div class="flex-box">
<p>Once upon a time in a ...</p>
<button>Read More...</button>
</div>

<h1>Only Button</h1>         //button with flex box
<div class="flex-box-2">
  <button>The Button</button>
</div>

<h1>Multiple Buttons</h1>
<div class="flex-box-2">
  <button>Button 1</button>
  <button>Button 2</button>
</div>