Multiline labels on the {align} environment are rendered with offset

[agronskiy]

Issue Summary

When creating a multiline tagged {align} environment, the labels' heights are computed wrongly for chtml output (ok for svg). See screenshots below.

No special changes to fonts or scaling were made (see GitHub repo below).

Steps to Reproduce:

Minimum example is in https://github.com/agronskiy/mathjax-label-issue

1. Clone it
2. Compare chtml.html and svg.html rendering:

vs

Technical details:

• MathJax Version: 3.1.2
• Client OS: Mac OS X 10.15.7
• Browser: Chrome 87.0.4280.88 (Official Build) (x86_64)

Supporting information:

• Minimal example: https://github.com/agronskiy/mathjax-label-issue
• No messages in Chrome's dev console
• In Safari, it is similar:

Thanks for any hints and for the awesome product!

[dpvc]

It looks like there may be accumulated round-off problems in WebKit for this. The exact same HTML renders properly in Firefox. I'll have to look into it and see what I can do.

[dpvc]

I have made a PR to resolve the issue (along with a bunch of other table issues).