<section>:

<h1></h1>
<section>
  <h2></h2>
  <p>
    
  </p>
</section>

<section>
  <h2></h2>
  <p>
    
    ...
  </p>
</section>

h1,
h2 {
  margin: 0;
}

<div>
  <h2></h2>
  <p></p>
</div>

<section>
  <h2></h2>
  <p></p>
</section>

<section>
  <a href="#"></a>
  <a href="#"></a>
</section>

<section>
  <button class="reply"></button>
  <button class="reply-all"></button>
  <button class="fwd"></button>
  <button class="del"></button>
</section>