title: position fixed with placeholder
body: <p>I have a div with dynamic height.
  This div needs to be position: fixed.
  The following div should vertically start where the first div ends.</p>
  
  <p>The reason is that the div is a header that should stay on top. However, the content should start right after the header. So that when the page is scrolled the header stays fixed and the rest scrolls as usual. Setting a margin-top for the content usually does the trick but this type the header has a dynamic height. Any ideas?</p>
  
  <p>EDIT: One solution I could think of is printing the header twice and setting the second to position: relative and visibility: hidden. While it should work it seems a terrible solution.</p>