# Mathjax rendering incorrectly in edit preview.

Update: I later found that anything I edited on Main didn't render properly in Preview. On a whim, I de-activated the LocalCDN plugin I installed after seeing a-super-easy-way-to-speedup-mathjax-loading-with-localcdn-add-on on Meta. Everything is now fine and my edits are previewing with alacrity.

I was editing am301's answer on this question and found that the Mathjax didn't render properly in the preview window. I have since copied the answer into a new question from where this screen shot is taken:

You can see that the first sum is rendered correctly but the second formula is not, nor are the subsequent ones. The peculiar thing is that if I copy it into the sandbox on Meta, it all renders perfectly. I'm using Firefox on Windows 7 and I've tried different Mathjax renderers.

What is causing the Mathjax to be rendered incorrectly, and why is it different on Meta?

• I'm having it render fine on my end (Mac OS X Catalina, Safari 14.1.1). Two observations that seem unrelated: (1) the answer uses $$...\\...$$ which is not legal LaTeX, though I have no problems with it in Mathjax on Math.SE. (2) I also have mathjax acting different on main and meta; in my case, i notice that formulas have 1 or 2 pixels cut off from the top or bottom in main, but are perfectly rendered here Nov 28 '21 at 3:09
• @CalvinKhor, thanks for your response. See the update on my question; it may introduce more questions but at least I can the edit previews are working again. Dec 1 '21 at 20:57
• Interesting; perhaps there is an updated version of localCDN that may fix it in the future... Dec 2 '21 at 2:26
• @PeterPhipps might I suggest writing your update as an answer so this question can be marked as answered? Dec 2 '21 at 23:50

Following some more experimentation, I found that anything I edited on Main didn't render properly in Preview, and it didn't always work on meta either.

On a whim, I de-activated the LocalCDN plugin I installed after seeing a-super-easy-way-to-speedup-mathjax-loading-with-localcdn-add-on on math.meta. Everything is now fine and my edits are previewing with alacrity.

I have had a quick look on the localcdn website to see if it says anything about unsupported versions of Windows etc, but there's nothing.