HTML CSS
(a quick guide)
<h1>MY STORY</h1> <h2>CHAPTER 1</h2> <p>A tragic pedal overflows.</p> <hr> <h2>CHAPTER 2</h2> <p>A routine silver speaks.</p> <hr>
<style> .line { border-bottom: 1px solid red } </style> <section class="line"> <h2>CHAPTER 1</h2> <p>The trade complains.</p> </section> <section class="line"> <h2>CHAPTER 2</h2> <p>The guide composes.</p> </section>
<hr> has an actual semantic meaning - Used to mark "end of a section".
border is purely cosmetic.
Conclusion - Both works.
Modern search engines can actually understand the content well enough, even without <hr> or border.