<!DOCTYPE html> <html class="reftest-wait"> <head> <style type="text/css"> .separator, #child { height: 20px; background-color: blue; } #multi-column { background-color: yellow; } #child { margin: 20px 0; } </style> <script type="text/javascript"> function test() { document.getElementById('multi-column').style.MozColumnCount = 1; document.getElementById('multi-column').style.columnCount = 1; document.documentElement.removeAttribute('class'); } document.addEventListener('MozReftestInvalidate', test, false); </script> </head> <body> <div class="separator"></div> <div id="multi-column"> <div id="child"></div> </div> <div class="separator"></div> </body> </html>