title: Letter inside square
body: <p>I would like to create a text like that:
  <img src="https://i.stack.imgur.com/Xq2jm.png" alt="enter image description here"></p>
  
  <p><br>
  My question is, how can I create it using CSS?<br>
  The closest solution I've found was unicode with circles:<br>
  ①②③<br></p>