<html xmlns="http://www.w3.org/1999/xhtml" xmlns:xul="http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul" style="opacity: 0.2;"> <head> <script> function x() { document.documentElement.style.counterReset = "chicken"; document.body.offsetHeight; } </script> </head> <body onload="setTimeout(x, 0);">Foo</body> <xul:listbox/> </html>