I’m trying to add excerpts to posts on this page:

https://axxs.io/articles/

I found the file containing the relevant code and changed it to the following:

<div class="blog-body">
<h3><a href="'.get_permalink().'">'.get_the_title().'</a></h3>
<p><?php the_excerpt(); ?></p>
</div>

But it renders the PHP out as code. What am I doing wrong?