<html xmlns="http://www.w3.org/1999/xhtml"> <head> <style id="style">p { color: red; }</style> <script> <![CDATA[ function boom() { var styleText = "p { color: green; }"; // Make 2^17 rules for (var i = 0; i < 17; ++i) { styleText += styleText; } document.getElementById("style").firstChild.data = styleText; document.body.appendChild(document.createElementNS("http://www.w3.org/1998/Math/MathML", "mrow")); } ]]> </script> </head> <body onload="boom();"><p>This should be green</p></body> </html>