The preview does not look the same as the final rendering

[fred-wang]

I suspect this is because some attributes or style are not allowed in the TeXZilla edition box.

For example single variable are not italic in release. I suspect this is because Gecko uses the _moz attribute for the implementation. However, this is fixed by Bug 114365.

Similarly, the font-family on the math seems to be reset.

[rgaiacs]

I don't know how to fix this.

[fred-wang]

the machine on which the screenshot was take does not seem to have the recommended math fonts installed.

[fred-wang]

One of the issue is that

https://github.com/ckeditor/ckeditor-dev/blob/master/skins/moono/reset.css#L49

defines font: normal normal normal 12px Arial,Helvetica,Tahoma,Verdana,Sans-Serif;.

However, I'm not sure Kuma has these rules:
https://github.com/mozilla/kuma/tree/master/media/js/libs/ckeditor/skins
so perhaps it will work on MDN.