title: Arranging and positioning two divs below each other in CSS
body: <p>I'm new to CSS, so this question might be dead simple. I am laying out a website and am stuck with positioning.</p>
  
  <p>On the site, I have a middle section in which there is a header with some scrollable content underneath. Here's the relevant CSS for the header div:</p>
  
  <pre><code>#header {
      position: absolute;
      margin-left: auto;
      margin-right: auto;
      width: 100%;
      height: auto;
  }
  </code></pre>
  
  <p>Now, I simply want the content div to immediately follow underneath, and can't figure out how to do that. </p>
  
  <pre><code>position: relative; 
  top: 0; 
  </code></pre>
  
  <p>doesn't seem to work (which I initially expected to). Both divs are on the same logical level and wrapped inside the middle section div. I am probably missing something extremely obvious and easy.</p>