<!DOCTYPE html>
<html>
  <head>
    <style>
      div {
        margin: 0;
        padding: 10px;
        font-size: 40px;
        height: 100px;
        width: 100px;
        border: 1px solid red;
        outline: none;
      }
    </style>
  </head>
  <body onload="document.getElementById('i').focus()">
    <div contenteditable id="i"></div>
  </body>
</html>