<html> <head> <style type="text/css"> body { font-family: monospace; width: 4ch; } body::first-line { } body *::before { content: 'w';} </style> <script type="text/javascript"> function boom() { var de = document.documentElement; var body = document.body; var span = document.createElementNS("http://www.w3.org/1999/xhtml", "span"); var r1 = document.createElementNS("http://www.w3.org/1998/Math/MathML", "mrow"); var mmm = document.createElementNS("http://www.w3.org/1998/Math/MathML", "mmultiscripts"); body.appendChild(span); r1.appendChild(document.createElementNS("http://www.w3.org/1998/Math/MathML", "mrow")); body.appendChild(r1); body.appendChild(mmm); de.offsetHeight; r1.appendChild(document.createElementNS("http://www.w3.org/1998/Math/MathML", 'mrow')); de.offsetHeight; mmm.appendChild(document.createElementNS("http://www.w3.org/1998/Math/MathML", 'mrow')); de.offsetHeight; } window.addEventListener("load", boom, false); </script> </head> <body></body> </html>