Chat App Illustration HTML and CSS

This is my solution to this challenge, and while coding, I had some questions about semantic HTML tags.

• What should I use to group cell elements? <div>, <section>, <article>, I read Mozilla's HTML tag documentation, but I didn't find any that fit this situation besides the <div>, which serves to group generic elements.

<div class="cellphone">
  <div class="app-header"></div>
  <div class="app-chat"></div>
</div>

// or something like:

<section class="cellphone">
  <header class="app-header"></div>
  <div class="app-chat"></div>
</div>

• Another question I had was, how can I define, in this situation, what is part of the main content? Would it be my <article> tag (I don't know if it's semantically correct) or my <div class="cellphone">? In this case, can the ".cellphone" be considered an illustration and, therefore, only the <article> will be part of the <main>?

Besides, that's it, thanks, and Good Coding.