title: position fixed outside on the container issue
body: <p>what i'm trying to do is make a container that contain a fixed line in the middle what i want to do is to cut the line outside on the section</p>
  <p>the problem with this divs and its styles :</p>
  <p>HTML :</p>
  <pre><code>&lt;div class=&quot;stem-wrapper&quot;&gt;
      &lt;div class=&quot;stem&quot;&gt;&lt;/div&gt;
      &lt;div class=&quot;stem-background&quot;&gt;&lt;/div&gt;
  &lt;/div&gt;
  </code></pre>
  <p><a href="https://codepen.io/userJ/pen/yvxLpK" rel="nofollow noreferrer">codepen</a></p>
  <p>if you remove the background from <strong>section header</strong> you will see what i mean , i want to make the fixed only contain inside the section not outside of the container .</p>