How can I reorder my divs using only CSS?

Question

Given a template where the HTML cannot be modified because of other requirements, how is it possible to display (rearrange) a div above another div

Answer 1

This solution uses only CSS and works with variable content

#wrapper   { display: table; }
#firstDiv  { display: table-footer-group; }
#secondDiv { display: table-header-group; }