Responsive Frontend Mentor - QR code component using flexbox.

Good job on your project!

One good practice is knowing when to use classes. Since this project is really small (code wise), classes are not necessary. This project uses only one of each element; main, img, heading and p.

Once your project start to get larger, then classes are definitely required. To keep things classes clean and easy to read you can use the BEM naming convention. Here's an article that explains more in detail. https://codeburst.io/understanding-css-bem-naming-convention-a8cca116d252

Also, each element serves a purpose. For example, the header element is usually reserved for introductory content; nav and hero content. https://developer.mozilla.org/en-US/docs/Web/HTML/Element

So for this project, you use either the main or article element.

Hope this helps in your coding journey!