Horizontal double linesnot rendering correctly in CD

[fweth]

Issue Summary

In the CD environment, @= should render a horizontal or vertical double line (see documentation) but the horizontal line renders as a single line.

Steps to Reproduce:

Try render something like this:

\begin{CD}
B @> g >> A \\
@| @VV f V \\
B @= A
\end{CD}

Or just paste it here: https://saxarona.github.io/mathjax-viewer/

I also checked on HackMD, which implements MathJax. In KaTeX based environments, this is not a problem.

[dpvc]

I can not reproduce your issue. The output is correct for me:

It works correctly in my own test file, and in the viewer that you link to.

You have not given the full details requested in the issue template, which includes the browser and OS you are using, and what versions they are.

Note that the MathJax version in your link viewer is 4.0.0-beta.4, but the official v4.0.0 is out. It is always best to update to the current version of software to see if the issue is resolved there before posting a bug report. In this case, the handling of stretchy characters has changed since beta.4, and I suspect that that will produce the result you are looking for (I suspect the character is being clipped so that one of the lines isn't showing).