Below is a code snippet where I am implementation login with the Facebook.
<script async defer crossorigin="anonymous" src="https://connect.facebook.net/en_GB/sdk.js#xfbml=1&version=v16.0&appId=app_id_here&autoLogAppEvents=1"
nonce="nonce_here"></script>
<div class="fb-login-button" data-width="" data-size="large" data-button-type="continue_with" data-layout="" data-auto-logout-link="false" data-use-continue-as="false"></div>
How can I make the button circular and set its width and height so it just displays the icon?