QR code component with CSS flexbox

Tajwar,

your project looks amazing, using the box-shadow property is pretty simple, however, the best advice that I can give you when not fully understanding how to use a property is to refer to either (https://www.w3schools.com/) or (https://developer.mozilla.org/en-US/) as you will be able to have an accurate reference on anything related to CSS and HTML plus much more, these websites are your best friends when it comes to learning such technologies.

here is a link that explains exactly what the "box-shadow" property it, its uses, semantics etc etc. https://www.w3schools.com/cssref/css3_pr_box-shadow.php

I hope this comment is comes handy to you.

good luck and happy coding my friend.