title: How do I change the shape of a button in MUI using theme?
body: <p>So the documentation on <code>Button</code> component has various sections and also a Codesandbox linked at <a href="https://codesandbox.io/s/npie4" rel="nofollow noreferrer">https://codesandbox.io/s/npie4</a></p>
  <p>However, there is nowhere mentioned how to change the shape of a button if needed.</p>
  <p><a href="https://i.stack.imgur.com/Tyc6l.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Tyc6l.png" alt="enter image description here" /></a></p>
  <p>I am using Google Material Sketch <a href="https://material.io/resources/theme-editor/" rel="nofollow noreferrer">file</a> and I want the buttons to be rounded</p>
  <p><a href="https://i.stack.imgur.com/FigpG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FigpG.png" alt="enter image description here" /></a></p>
  <p>How can I do that using the <code>theme</code> object so that in my entire app the <code>Button</code> component are always rounded?</p>