title: How to style a div content after fixed div header with dynamic height
body: <p>following situation:</p>
  
  <pre><code>&lt;body&gt;
   &lt;div style="position:fixed; width:100%"&gt;[place holder for header]&lt;/div&gt;
   &lt;div style="position:relative;width:100%;margin-top:100px"&gt;[content]&lt;/div&gt;
  &lt;/body&gt;
  </code></pre>
  
  <p>I need the header always visible and at the top, so this one should be with position:fixed.
  A problem occurs after self adjustments of the header - height. If the header is higher than 100px a part of the content is hidden.</p>
  
  <p>How can I (CSS) dynamically set the start position of the content div regarding the end of the header.</p>