<main>
  <div>
  <h1>Not nested &lt;h1></h1>
  <section>
    <h1>In a section &lt;h1></h1>
    <section>
      <h1>&lt;h1> in a nested section</h1>
      <section>
        <h1>&lt;h1> doubly nested in two sections</h1>
      </section>
    </section>
  </section>
    </div>
  <div>
   <h1>Actual &lt;h1></h1>
   <h2>Actual &lt;h2></h2>
   <h3>Actual &lt;h3></h3>
   <h4>Actual &lt;h4></h4>
  </div>
</main>

main {display: flex; gap: 100px;}