<article class="article">
  <h2>Article title</h2>
</article>

body {
  padding: 16px;
}

.article {
  max-width: 320px;
}

.article-text {
  color: tomato;
}
const article = document.querySelector(".article");
const htmlString = `<p class="article-text">Nullam quis ante. Vestibulum dapibus nunc ac augue. In consectetuer turpis ut velit.</p>
   <a class="link" href="#">Read more...</a>`;

// Replace += with = operator. See the difference? 
// Article title is lost because we overwrite element content.
article.innerHTML += htmlString;

External CSS

  1. https://cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/4.0.0-beta/css/bootstrap.min.css

External JavaScript

This Pen doesn't use any external JavaScript resources.