Issue with brackets when highlighted.

Created by: korirdesmond

Issue Summary

Hello. I'm experiencing an issue with curly brackets when highlighted, some parts aren't visible. When not highlighted, the brackets are rendered correctly. This is mostly visible on expressions with 4 rows. Here is the link to a test sandbox code .

Steps to Reproduce:

Check the MathML sample code here then highlight the equation.

Technical details:

• MathJax Version: 2.7.9 (https://cdnjs.cloudflare.com/ajax/libs/mathjax/2.7.9/MathJax.js?config=TeX-MML-AM_CHTML)
• Client OS: Mac OS Monterey 12.2.1
• Browser: Chrome (99.0.4844.51), safari

Supporting information:

• Here is a test sandbox https://codesandbox.io/s/mathjax-v2-forked-kg3i22?file=/index.html:430-517