<p>I’m a paragraph before the article.</p>

<article>
  <h2>The article</h2>
  <p>I’m a paragraph in the article.</p>
  <blockquote>
    <p>I’m a paragraph in a block quotation in the article.</p>
  </blockquote>
  <p>I’m another paragraph in the article.</p>
</article>

<p>I’m a paragraph after the article.</p>

<blockquote>
  <p>I’m a paragraph in a block quotation after the article.</p>
</blockquote>

p {
  background: aliceblue;
}

article p:not(blockquote *) {
  background: yellow;
}