working and tested code with mdb boostrap

  <div class="min-vh-100 d-flex flex-column 
                justify-content-between">
     
         <div> <!-- Wrapper (Without footer) -->
       
            <header>
             I am a header.
            </header>
      
            <article>
            I am an article!
            </article>
       
        </div> <!-- End: Wrapper (Without footer) -->
     
     
         <footer>
         I am a footer.
         </footer>
     
    </div>

source: https://stackoverflow.com/a/68836851/282234