mbourne
mbourne
Here's another possibility... 
@jason-s To add to this discussion, I've been experimenting using MathJax fonts with KaTeX processing to achieve slightly heavier (and thus more readable) math. You may be interested in this...
Presumably you've got double backslashes because you're feeding KaTeX via a javascript string, correct? It's not really clear why your "double backslash space" is not giving you what you expect...
This may be a Safari/MacOS issue, since it appears fine on each of Chrome, Opera, Edge and Firefox on Windows: 