title: How to create a square button?
body: <p>Thanks for @Justin XL and @grek40 help me so much.<br/>
  I must apologize for my poor English that troubles everyone so much.<br />
  And I think I need to improve this question to help any others in the furture.</p>
  
  <p>Here is the newest:<br/>
  I need to make a square button like this:
  <a href="https://i.stack.imgur.com/xSpWI.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/xSpWI.jpg" alt="enter image description here"></a></p>
  
  <p><br/>
  My programme is a fullscreen programme that different device has different window's size.<br/>
  So my square button should be can resizeable also beaucase I want to make a Reactive UI.<br/>
  And now how can I make a square button?<br/>
  Thank you.</p>